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U.S. Route 101 (US 101) is a major north–south
United States Numbered Highway The United States Numbered Highway System (often called U.S. Routes or U.S. Highways) is an integrated network of roads and highways numbered within a nationwide grid in the contiguous United States. As the designation and numbering of these hi ...
, stretching from
Los Angeles Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the List of municipalities in California, largest city in the U.S. state, state of California and the List of United States cities by population, sec ...
, California to
Tumwater, Washington Tumwater is a town in Thurston County, Washington, United States. The population was 25,350 at the 2020 census. It is situated near where the Deschutes River enters Budd Inlet, the southernmost point of Puget Sound; it also borders the state c ...
. The
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
portion of US 101 is one of the last remaining and longest U.S. Routes still active in the state, and the longest highway of any kind in California. US 101 was also one of the original national routes established in 1926. Significant portions of US 101 between the Los Angeles area and the San Francisco Bay Area follow El Camino Real, the commemorative route connecting the former Alta California's 21 missions. Although the highway has been superseded in overall importance for transportation through the state by
Interstate 5 Interstate 5 (I-5) is the main north–south Interstate Highway on the West Coast of the United States, running largely parallel to the Pacific coast of the contiguous U.S. from Mexico to Canada. It travels through the states of Californi ...
(I-5), US 101 continues to be the major coastal north–south route that links the
Greater Los Angeles Area Greater Los Angeles is the second-largest metropolitan region in the United States with a population of 18.5 million in 2021, encompassing five counties in Southern California extending from Ventura County in the west to San Bernardino Coun ...
, the Central Coast, the
San Francisco Bay Area The San Francisco Bay Area, often referred to as simply the Bay Area, is a populous region surrounding the San Francisco, San Pablo, and Suisun Bay estuaries in Northern California. The Bay Area is defined by the Association of Bay Area Go ...
, and the North Coast (Redwood Empire). Generally referred to as "101" by residents of Northern California, in
Southern California Southern California (commonly shortened to SoCal) is a geographic and cultural region that generally comprises the southern portion of the U.S. state of California. It includes the Los Angeles metropolitan area, the second most populous urban a ...
it is often called "The 101" (pronounced "the one oh one"). The highway has portions designated as the
Santa Ana Freeway The Santa Ana Freeway is one of the principal freeways in Southern California, connecting Los Angeles and its southeastern suburbs including the freeway's namesake, the city of Santa Ana. The freeway begins at its junction with the San Diego Free ...
, the
Hollywood Freeway The Hollywood Freeway is one of the principal freeways of Los Angeles, California (the boundaries of which it does not leave) and one of the busiest in the United States. It is the principal route through the Cahuenga Pass, the primary shortcut ...
, the
Ventura Freeway The Ventura Freeway is a freeway in southern California, United States, running from the Santa Barbara/ Ventura county line to Pasadena in Los Angeles County. It is the principal east-west route (designated north-south) through Ventura Count ...
, South Valley Freeway, and Bayshore Freeway, as well as El Camino Real in many non-freeway segments. The Redwood Highway, the northernmost segment of the highway, begins at the
Golden Gate The Golden Gate is a strait on the west coast of North America that connects San Francisco Bay to the Pacific Ocean. It is defined by the headlands of the San Francisco Peninsula and the Marin Peninsula, and, since 1937, has been spanned by t ...
and passes through the world's tallest and only extensive preserves of virgin, old-growth
coast redwood ''Sequoia sempervirens'' ()''Sunset Western Garden Book,'' 1995:606–607 is the sole living species of the genus '' Sequoia'' in the cypress family Cupressaceae (formerly treated in Taxodiaceae). Common names include coast redwood, coastal ...
trees.


Route description

US 101 is part of the
California Freeway and Expressway System The California Freeway and Expressway System is a system of existing or planned freeways and expressways in the U.S. state of California. It encompasses both State highways and federal highways in California. It is defined by Article 2 (comme ...
, and is part of the National Highway System,
a network of highways that are considered essential to the country's economy, defense, and mobility by the
Federal Highway Administration The Federal Highway Administration (FHWA) is a division of the United States Department of Transportation that specializes in highway transportation. The agency's major activities are grouped into two programs, the Federal-aid Highway Program ...
. Portions of US 101 are eligible to be included in the State Scenic Highway System. It is officially designated as a scenic highway by the
California Department of Transportation The California Department of Transportation (Caltrans) is an executive department of the U.S. state of California. The department is part of the cabinet-level California State Transportation Agency (CalSTA). Caltrans is headquartered in Sacr ...
from Goleta to Las Cruces in
Santa Barbara County Santa Barbara County, California, officially the County of Santa Barbara, is located in Southern California. As of the 2020 census, the population was 448,229. The county seat is Santa Barbara, and the largest city is Santa Maria. Santa Barba ...
, and through
Del Norte Coast Redwoods State Park Del Norte Coast Redwoods State Park is a state park of California, United States, and a component of the Redwood National and State Parks. The property is about half old-growth forest of coast redwoods and includes of wild Pacific coastline. ...
in
Del Norte County ), in California , seat_type = County seat , seat = Crescent City , parts_type = Largest city , parts = Crescent City , unit_pref = US , area_total_sq_mi = 1230 , area_land_sq_mi = 1006 , area_water_sq_mi = 223 , elevation_max_footnote ...
. This designation means that there are substantial sections of highway passing through a "memorable landscape" with no "visual intrusions", where the potential designation has gained popular favor with the community.


Los Angeles to Ventura

The south terminus of US 101 is in
Los Angeles Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the List of municipalities in California, largest city in the U.S. state, state of California and the List of United States cities by population, sec ...
, about east of downtown Los Angeles at the
East Los Angeles Interchange The East Los Angeles Interchange is an interchange complex located in Boyle Heights, California, approximately 2.5 miles (4 km) east of Downtown Los Angeles. With its southern portion handling over 550,000 vehicles per day (2008 AADT), it is th ...
, also known as the "Commuters' Complex". This southernmost portion is named the
Santa Ana Freeway The Santa Ana Freeway is one of the principal freeways in Southern California, connecting Los Angeles and its southeastern suburbs including the freeway's namesake, the city of Santa Ana. The freeway begins at its junction with the San Diego Free ...
, inheriting that title as the northerly extension of the roadway now known as
I-5 Interstate 5 (I-5) is the main north–south Interstate Highway on the West Coast of the United States, running largely parallel to the Pacific coast of the contiguous U.S. from Mexico to Canada. It travels through the states of Californi ...
. US 101 heads north for before merging with the western end of the San Bernardino Freeway (I-10). After merging with westbound traffic from the San Bernardino Freeway (I-10), US 101 then proceeds northwest via the Downtown Slot under the northern edge of Los Angeles' Civic Center to State Route 110 (SR 110) at the
Four Level Interchange The Four Level Interchange (officially the Bill Keene Memorial Interchange) is the first stack interchange in the world. Completed in 1949 and fully opened in 1953 at the northern edge of Downtown Los Angeles, California, United States, it connect ...
. From here, US 101 becomes the
Hollywood Freeway The Hollywood Freeway is one of the principal freeways of Los Angeles, California (the boundaries of which it does not leave) and one of the busiest in the United States. It is the principal route through the Cahuenga Pass, the primary shortcut ...
. It then passes through the L.A. neighborhoods of
Echo Park Echo Park is a neighborhood in the east-central region of Los Angeles, California. Located to the northwest of Downtown, it is bordered by Silver Lake to the west and Chinatown to the east. The culturally diverse neighborhood has become known f ...
,
Silver Lake Silver is a chemical element with the Symbol (chemistry), symbol Ag (from the Latin ', derived from the Proto-Indo-European wikt:Reconstruction:Proto-Indo-European/h₂erǵ-, ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, whi ...
, and
Los Feliz LOS, or Los, or LoS may refer to: Science and technology * Length of stay, the duration of a single episode of hospitalisation * Level of service, a measure used by traffic engineers * Level of significance, a measure of statistical significanc ...
and heads to Hollywood and up through the
Cahuenga Pass The Cahuenga Pass (, ; Tongva: ''Kawé’nga'') is a low mountain pass through the eastern end of the Santa Monica Mountains in the Hollywood Hills district of the City of Los Angeles, California. It has an elevation of . The Cahuenga Pass connec ...
before reaching the San Fernando Valley. US 101 passes right next to the
Universal Studios Hollywood Universal Studios Hollywood is a film studio and theme park in the San Fernando Valley area of Los Angeles County, California. About 70% of the studio lies within the unincorporated county island known as Universal City while the rest lies w ...
and then intersects with SR 134 and SR 170 at the interchange known as the
Hollywood Split The Hollywood Split (officially Bruce T. Hinman Memorial Interchange) is a freeway interchange in the San Fernando Valley area of Los Angeles, California. The interchange is officially named in the memory of California Highway Patrol officer Bruc ...
. Here, the alignment of US 101 shifts to the alignment of SR 134 (i.e. heading northbound, the road's alignment turns left, or westbound) and thereafter is referred to as the
Ventura Freeway The Ventura Freeway is a freeway in southern California, United States, running from the Santa Barbara/ Ventura county line to Pasadena in Los Angeles County. It is the principal east-west route (designated north-south) through Ventura Count ...
until it reaches Ventura. Though confusing, the "Hollywood Freeway" name continues northward from this interchange on SR 170, and the "Ventura Freeway" name continues eastward to SR 134. From the Hollywood Split, US 101 is an east–west highway (until it reaches
Gaviota State Park Gaviota State Park is a state park of California, United States. It is located in southern Santa Barbara County, California, about west of the city of Santa Barbara. One of three state parks along the Gaviota Coast, it extends from the Pacif ...
in
Santa Barbara County Santa Barbara County, California, officially the County of Santa Barbara, is located in Southern California. As of the 2020 census, the population was 448,229. The county seat is Santa Barbara, and the largest city is Santa Maria. Santa Barba ...
where it shifts back to a north–south alignment). It meets with I-405 in Sherman Oaks, an interchange which holds claim to the most traveled intersection in the nation. The east–west geographical alignment of the Ventura Freeway and the north–south designation which appears on the freeway signs can be confusing to visitors; the same freeway entrance can often be signed as "101 North" and "101 West"; this is most common in the San Fernando Valley where the local E/W signing does not match the Caltrans' proper statewide N/S designation. After the
Conejo Grade The Conejo Grade is a 7% grade incline on a section of US 101 (the Ventura Freeway). Also known as the Camarillo Grade, it links Thousand Oaks and cities of the Conejo Valley, with Camarillo and the cities on the Oxnard Plain. With a summit ...
, which is a 7% grade incline, the freeway enters the
Oxnard Plain The Oxnard Plain is a large coastal plain in southwest Ventura County, California, United States surrounded by the mountains of the Transverse ranges. The cities of Oxnard, Camarillo, Port Hueneme and much of Ventura as well as the unincorpora ...
and runs concurrent with SR 1 for the first time. Upon reaching Ventura, there is an interchange with SR 126, which runs east to
Santa Clarita Santa Clarita (; Spanish for "Little St. Clare") is a city in northwestern Los Angeles County in the U.S. state of California. With a 2020 census population of 228,673, it is the third-largest city by population in Los Angeles County, the 17t ...
.


Central Coast

North of Santa Barbara, US 101 switches intermittently between freeway and expressway status (i.e. there is occasional cross-traffic), but there are no traffic signals until
San Francisco San Francisco (; Spanish for " Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the fourth most populous in California and 17th ...
. The last traffic signals along this stretch of the route were removed in 1991 when the section through downtown Santa Barbara was constructed to freeway standards after years of disagreement over the impact that the original elevated design would have on the community. From Ventura and through Santa Barbara, US 101 closely follows the
Gaviota Coast The Gaviota Coast in Santa Barbara County, California is a rural coastline along the Santa Barbara Channel roughly bounded by the city of Goleta, California, Goleta on the south and the north boundary of the county on the north. This last undeve ...
(generally no more than from the
shore A shore or a shoreline is the fringe of land at the edge of a large body of water, such as an ocean, sea, or lake. In physical oceanography, a shore is the wider fringe that is geologically modified by the action of the body of water past a ...
) until
Gaviota State Park Gaviota State Park is a state park of California, United States. It is located in southern Santa Barbara County, California, about west of the city of Santa Barbara. One of three state parks along the Gaviota Coast, it extends from the Pacif ...
, about west of Goleta. At Gaviota State Park, the highway shifts back from an east–west highway to a north–south alignment. About north of this point, the northbound lanes pass through the
Gaviota Tunnel The Gaviota Tunnel (officially known as the Gaviota Gorge Tunnel) is a tunnel on U.S. Route 101 and California State Route 1 completed in 1953 in the center of Gaviota State Park, northwest of Santa Barbara, California on the Gaviota Coa ...
. A few miles north of the Gaviota Tunnel, SR 1 splits from US 101 and heads northwest, running along the Pacific coastline parallel and to the west of US 101. US 101 passes through Buellton, Los Alamos, Orcutt, Santa Maria, and
Nipomo Nipomo (; Chumash: ''Nipumuʔ'') is a unincorporated town in San Luis Obispo County, California, United States. The population was 16,714 for the 2010 census and grew to 18,176 for the 2020 census. For statistical purposes, the United States ...
. South of Santa Maria, US 101 widens from a four-lane highway to a six-lane freeway. SR 166 joins US 101 for about before splitting just north of the city limits, while US 101 continues as a four-lane freeway before reverting to expressway status north of Nipomo. Farther north, SR 1 rejoins US 101 between
Pismo Beach Pismo Beach (Chumash: ''Pismuʔ'') is a city in the southern portion of San Luis Obispo County, in the Central Coast area of California, United States. The estimated population was 8,072 at the 2020 census, up from 7,655 in the 2010 census. It ...
and
San Luis Obispo San Luis Obispo (; Spanish for " St. Louis the Bishop", ; Chumash: ''tiłhini'') is a city and county seat of San Luis Obispo County, in the U.S. state of California. Located on the Central Coast of California, San Luis Obispo is roughly hal ...
. Then US 101 takes an inland route through the
Salinas Valley The Salinas Valley is one of the major valleys and most productive agricultural regions in California. It is located west of the San Joaquin Valley and south of San Francisco Bay and the Santa Clara Valley. The Salinas River, which geologically ...
, while Highway 1 heads northwest, running along the Pacific coastline in California, parallel and to the west of US 101. A steep segment (7% grade) between
San Luis Obispo San Luis Obispo (; Spanish for " St. Louis the Bishop", ; Chumash: ''tiłhini'') is a city and county seat of San Luis Obispo County, in the U.S. state of California. Located on the Central Coast of California, San Luis Obispo is roughly hal ...
and
Atascadero Atascadero (Spanish language, Spanish for "Mire") is a city in San Luis Obispo County, California, San Luis Obispo County, California, about equidistant from Los Angeles and San Francisco on U.S. Route 101 in California, U.S. Route 101. Atascade ...
is known as the Cuesta Grade. North of Atascadero, the highway joins SR 46 for about through
Paso Robles Paso Robles ( ), officially El Paso de Robles (Spanish for "The Pass of Oaks"), is a city in San Luis Obispo County, California, United States. Located on the Salinas River approximately north of San Luis Obispo, the city is known for its hot ...
. From Paso Robles to Salinas, US 101 is an expressway known as the Salinas River Valley Highway, since the Salinas River Valley extends from Santa Margarita to the SR 156 junction in Prunedale. US 101 resumes freeway status between San Miguel and King City, bypassing the smaller towns of Camp Roberts,
Bradley Bradley is an English surname derived from a place name meaning "broad wood" or "broad meadow" in Old English. Like many English surnames Bradley can also be used as a given name and as such has become popular. It is also an Anglicisation of t ...
, and San Ardo, as well as the San Ardo Oil Field about south of San Ardo. Near this point, the wide agricultural bottomlands of the Salinas Valley begins. North of King City, US 101 once again switches intermittently between freeway and expressway status, passing through Greenfield, Soledad, Gonzales, and Chualar before reaching Salinas. Shortly after leaving Salinas, US 101 joins SR 156 in Prunedale for about . After crossing the
San Benito County San Benito County (; ''San Benito'', Spanish for " St. Benedict"), officially the County of San Benito, is a county located in the Coast Range Mountains of the U.S. state of California. As of the 2020 census, the population was 64,209. The co ...
line, SR 156 splits from US 101 near San Juan Bautista while US 101 continues northward mostly as a four-lane highway until it reaches Gilroy.


San Francisco Bay Area

US 101 crosses the Pajaro River into
Santa Clara County Santa Clara County, officially the County of Santa Clara, is the sixth-most populous county in the U.S. state of California, with a population of 1,936,259, as of the 2020 census. Santa Clara County and neighboring San Benito County together f ...
as a four-lane highway, with an interchange at SR 25 a few miles later. Upon reaching Gilroy, it becomes the South Valley Freeway (as in South
Santa Clara Valley The Santa Clara Valley is a geologic trough in Northern California that extends 90 miles (145 km) south–southeast from San Francisco to Hollister. The longitudinal valley is bordered on the west by the Santa Cruz Mountains and on the east ...
), and at the same time, it expands to three lanes in each direction. It then enters
Silicon Valley Silicon Valley is a region in Northern California that serves as a global center for high technology and innovation. Located in the southern part of the San Francisco Bay Area, it corresponds roughly to the geographical areas San Mateo Coun ...
when reaching
Morgan Hill Morgan Hill is a city in Santa Clara County, California, at the southern tip of Silicon Valley, in the San Francisco Bay Area. Morgan Hill is an affluent residential community, the seat of several high-tech companies, and a dining, entertainmen ...
, and shortly afterwards expands to four lanes in each direction, with an
HOV A high-occupancy vehicle lane (also known as an HOV lane, carpool lane, diamond lane, 2+ lane, and transit lane or T2 or T3 lanes) is a restricted traffic lane reserved for the exclusive use of vehicles with a driver and one or more passengers, i ...
lane in the middle, before reaching San Jose. From San Jose to San Francisco, US 101 is known as the Bayshore Freeway as it passes through
Palo Alto Palo Alto (; Spanish for "tall stick") is a charter city in the northwestern corner of Santa Clara County, California, United States, in the San Francisco Bay Area, named after a coastal redwood tree known as El Palo Alto. The city was es ...
and the other major communities along the
San Francisco Peninsula The San Francisco Peninsula is a peninsula in the San Francisco Bay Area that separates San Francisco Bay from the Pacific Ocean. On its northern tip is the City and County of San Francisco. Its southern base is Mountain View, south of Palo Alt ...
. US 101 is called the
James Lick Freeway James is a common English language surname and given name: *James (name), the typically masculine first name James * James (surname), various people with the last name James James or James City may also refer to: People * King James (disambiguat ...
, named for
James Lick James Lick (August 25, 1796 – October 1, 1876) was an American real estate investor, carpenter, piano builder, land baron, and patron of the sciences. The wealthiest man in California at the time of his death, Lick left the majority of his es ...
, a philanthropist, from the San Francisco county/city line, through the interchange with
I-280 Interstate 280 may refer to multiple highways, all of which are or were related to Interstate 80: * Interstate 280 (California), a north–south freeway running from San Jose to San Francisco * Interstate 280 (Iowa–Illinois), part of the beltway ...
at the Alemany Maze, until the junction with the San Francisco Skyway (
I-80 Interstate 80 (I-80) is an east–west transcontinental freeway that crosses the United States from downtown San Francisco, California, to Teaneck, New Jersey, in the New York metropolitan area. The highway was designated in 1956 as one o ...
) and the
Central Freeway The Central Freeway is a roughly one-mile (1.5 km) elevated freeway in San Francisco, California, United States, connecting the Bayshore/James Lick Freeway (US 101 and I-80) with the Hayes Valley neighborhood. Most of the freeway is part ...
near the city's
Civic Center A civic center or civic centre is a prominent land area within a community that is constructed to be its focal point or center. It usually contains one or more dominant public buildings, which may also include a government building. Recently, the ...
. US 101 continues in a northwestern direction on the Central Freeway, and then leaves the freeway, on
Mission Street Mission Street is a north-south arterial thoroughfare in Daly City and San Francisco, California that runs from Daly City's southern border to San Francisco's northeast waterfront. The street and San Francisco's Mission District through which it ...
(northbound) and South Van Ness Avenue (southbound), to run north on
Van Ness Avenue Van Ness Avenue is a north–south thoroughfare in San Francisco, California. Originally named Marlette Street, the street was renamed Van Ness Avenue in honor of the city's sixth mayor, James Van Ness. The main part of Van Ness Avenue runs fro ...
. At the intersection of Van Ness Avenue and Lombard Street, US 101 heads west on Lombard Street, and then on Richardson Avenue, entering
The Presidio ''The Presidio'' is a 1988 American crime film directed by Peter Hyams and starring Sean Connery and Mark Harmon. Hyams also handled the cinematography and the score was composed by Bruce Broughton. Plot At the Presidio Army base in San Franci ...
, where it becomes a divided highway again (the Presidio Parkway). It is then joined by Route 1 before approaching and crossing the Golden Gate Bridge. From San Francisco north the highway is heavily traveled by commuters through to
Windsor Windsor may refer to: Places Australia * Windsor, New South Wales ** Municipality of Windsor, a former local government area * Windsor, Queensland, a suburb of Brisbane, Queensland **Shire of Windsor, a former local government authority around Wi ...
, just north of
Santa Rosa Santa Rosa is the Italian, Portuguese and Spanish name for Saint Rose. Santa Rosa may also refer to: Places Argentina *Santa Rosa, Mendoza, a city * Santa Rosa, Tinogasta, Catamarca * Santa Rosa, Valle Viejo, Catamarca * Santa Rosa, La Pampa * S ...
. North of the Golden Gate Bridge, US 101 enters Marin County and is known as the Redwood Highway. After crossing the bridge, US 101 climbs the
Waldo Grade The Waldo Grade is a highway grade between the Golden Gate Bridge and Marin City along U.S. Route 101 and State Route 1. It is defined as the stretch of roadway between the Spencer Offramp and Marin City, within the city of Sausalito. This gra ...
and passes through the Robin Williams Tunnel, the only one of its kind in (the other being the
Gaviota Tunnel The Gaviota Tunnel (officially known as the Gaviota Gorge Tunnel) is a tunnel on U.S. Route 101 and California State Route 1 completed in 1953 in the center of Gaviota State Park, northwest of Santa Barbara, California on the Gaviota Coa ...
in
Santa Barbara County Santa Barbara County, California, officially the County of Santa Barbara, is located in Southern California. As of the 2020 census, the population was 448,229. The county seat is Santa Barbara, and the largest city is Santa Maria. Santa Barba ...
). Upon exiting the tunnel, it passes above the hillside town of
Sausalito Sausalito (Spanish for "small willow grove") is a city in Marin County, California, United States, located southeast of Marin City, south-southeast of San Rafael, and about north of San Francisco from the Golden Gate Bridge. Sausalito's ...
and descends to
Richardson Bay Richardson Bay (originally Richardson's Bay) is a shallow, ecologically rich arm of San Francisco Bay, managed under a Joint Powers Agency of four northern California cities. The Richardson Bay Sanctuary was acquired in the early 1960s by the ...
, where SR 1 splits from the freeway and heads to the coast. US 101 then passes through
Mill Valley Mill Valley is a city in Marin County, California, Marin County, California, United States, located about north of San Francisco via the Golden Gate Bridge and from Napa Valley. The population was 14,231 at the 2020 United States Census, 2020 ...
, Corte Madera, Larkspur, San Rafael and
Novato Novato ( Spanish for "Novatus") is a city in Marin County, California, in the North Bay region of the Bay Area. At the 2020 census, Novato had a population of 53,225. History What is now Novato was originally the site of several Coast Miwok ...
, before entering Sonoma County. The section between Novato in Marin County and
Petaluma Petaluma (Miwok: ''Péta Lúuma'') is a city in Sonoma County, California, located in the North Bay region of the San Francisco Bay Area. Its population was 59,776 according to the 2020 census. Petaluma's name comes from the Miwok village nam ...
in
Sonoma County Sonoma County () is a county located in the U.S. state of California. As of the 2020 United States Census, its population was 488,863. Its county seat and largest city is Santa Rosa. It is to the north of Marin County and the south of Mendocino ...
changes from its original six or eight lanes through Marin to four lanes, creating a bottleneck, and is thus called the "Novato Narrows" by locals. The Narrows continue up to the county line between Marin and Sonoma Counties. The entire area between Novato and Petaluma is also the voter approved Novato–Petaluma Community Separator, which forbids most development. Upon entering Sonoma County, the freeway widens again to six lanes from the county line to
Windsor Windsor may refer to: Places Australia * Windsor, New South Wales ** Municipality of Windsor, a former local government area * Windsor, Queensland, a suburb of Brisbane, Queensland **Shire of Windsor, a former local government authority around Wi ...
, passing through
Petaluma Petaluma (Miwok: ''Péta Lúuma'') is a city in Sonoma County, California, located in the North Bay region of the San Francisco Bay Area. Its population was 59,776 according to the 2020 census. Petaluma's name comes from the Miwok village nam ...
, Cotati,
Rohnert Park Rohnert Park is a city in Sonoma County, California, United States, located approximately north of San Francisco. The population at the 2020 United States Census was 44,390. It is an early planned city and is the sister city of Hashimoto in ...
, and
Santa Rosa Santa Rosa is the Italian, Portuguese and Spanish name for Saint Rose. Santa Rosa may also refer to: Places Argentina *Santa Rosa, Mendoza, a city * Santa Rosa, Tinogasta, Catamarca * Santa Rosa, Valle Viejo, Catamarca * Santa Rosa, La Pampa * S ...
. Upon reaching Windsor, the freeway returns to two lanes in each direction, crossing the Russian River in
Healdsburg Healdsburg is a city located in Sonoma County, in California's Wine Country. At the 2010 census, the city had a population of 11,254. Owing to its three most important wine-producing regions (the Russian River, Dry Creek, and Alexander Valle ...
and then following the river up the
Alexander Valley The Alexander Valley (Wappo: Unutsawaholmanoma, "Toyon Bush Berry Place") is a Californian American Viticultural Area (AVA) just north of Healdsburg in Sonoma County. It is home to many wineries and vineyards, as well as the city of Cloverdale. ...
. SR 128 joins US 101 in the town of Geyserville before splitting just north of Cloverdale. US 101 then heads up a steep hill just before leaving Sonoma County and entering
Mendocino County Mendocino County (; ''Mendocino'', Spanish for "of Mendoza) is a county located on the North Coast of the U.S. state of California. As of the 2020 census, the population was 91,601. The county seat is Ukiah. Mendocino County consists whol ...
.


North Coast

US 101 crosses into
Mendocino County Mendocino County (; ''Mendocino'', Spanish for "of Mendoza) is a county located on the North Coast of the U.S. state of California. As of the 2020 census, the population was 91,601. The county seat is Ukiah. Mendocino County consists whol ...
as a freeway for one mile (1.6 km), but then narrows to an expressway through the Russian River canyon and eventually a two-lane road south of Hopland, the first time since leaving
San Francisco San Francisco (; Spanish for " Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the fourth most populous in California and 17th ...
. Just before reaching Ukiah, US 101 becomes a four-lane freeway. In the community of Calpella, SR 20 merges with US 101 for the next to Willits. The freeway portion ends as the combined US 101 and SR 20 ascend the Ridgewood Summit, the highest elevation along the route's trek through California. As US 101 resumes freeway status just south of Willits, SR 20 splits from US 101 shortly before it suddenly reverts to a 2-lane undivided freeway and eventually a highway north of Willits. US 101 then widens to a four-lane expressway until the intersection with the western portion of SR 162, where it reverts to a two-lane road. North of
Laytonville Laytonville is a census-designated place (CDP) in Mendocino County, California, United States. It is located north-northwest of Willits, at an elevation of . The population was 1,152 at the 2020 census, down from 1,227 at the 2010 census. Geogr ...
, US 101 ascends Rattlesnake summit () before a descent to follow the
South Fork Eel River The South Fork Eel River is the largest tributary of the Eel River in north-central California in the United States. The river flows north from Laytonville to Dyerville/Founders' Grove where it joins the Eel River. The South Fork drains a long ...
and Eel River all the way to
Fortuna Fortuna ( la, Fortūna, equivalent to the Greek goddess Tyche) is the goddess of fortune and the personification of luck in Roman religion who, largely thanks to the Late Antique author Boethius, remained popular through the Middle Ages until at ...
near the mouth of the river. About northwest of Laytonville, US 101 becomes an undivided freeway near the community of Cummings. SR 271 is the old portion of US 101 through this area. At Leggett, US 101 meets SR 1 for the last time, and from this point until Piercy, US 101 runs along a section of highway with frequent landslides. Caltrans bypassed the most difficult section in 2009 with unique construction of two bridges known collectively as the Confusion Hill Bridges. This project, funded by an emergency act from the State Legislature, moved the highway across the Eel River away from the troubled spots to prevent disruption in commerce and travel from infrequent, but costly, winter closures on the main transportation route to the far North Coast. North of Piercy, the freeway portion again ends and the road narrows down to two lanes, before another stretch of divided highway. Arriving in Humboldt County, another narrow two lane portion of US 101 bisects
Richardson Grove State Park Richardson Grove State Park is located at the southernmost border of Humboldt County, south of Eureka, California, United States, and north of San Francisco. The year-round park, which has approximately , straddles US 101, causing the narrowe ...
. Just after the park boundary, the highway switches to a short undivided freeway and then eventually a divided freeway just before reaching Garberville. North of Garberville, US 101 reverts to an undivided freeway, which continuing north by northwest, passes through the Humboldt Redwoods State Park, California's third largest State Park and the site of the largest remaining Redwood old growth forest in the world. A preserved portion of the original, bypassed highway route, known as the
Avenue of the Giants The Avenue of the Giants is a scenic highway in northern California, United States, running through Humboldt Redwoods State Park. It is named after the coastal redwoods that tower over the route. The road is a former alignment of U.S. Route 101, ...
for the huge, centuries-old redwood trees, parallels the highway for over in southern Humboldt County. US 101 again switches to another stretch of divided freeway near the town Pepperwood before reverting to a short, 2-mile (3 km) expressway just north of Stafford. A short freeway then runs through
Rio Dell Rio Dell (Spanish: ''Río Dell'', meaning "Dell River") is a city in Humboldt County, California, United States. It is located on the west bank of the Eel River north of Scotia at an elevation of 161 feet (49 m). The population was 3,363 at t ...
before another short, 3-mile (5 km) expressway. Shortly before reaching the western terminus of SR 36, US 101 becomes a freeway again between
Fortuna Fortuna ( la, Fortūna, equivalent to the Greek goddess Tyche) is the goddess of fortune and the personification of luck in Roman religion who, largely thanks to the Late Antique author Boethius, remained popular through the Middle Ages until at ...
and
Eureka Eureka (often abbreviated as E!, or Σ!) is an intergovernmental organisation for research and development funding and coordination. Eureka is an open platform for international cooperation in innovation. Organisations and companies applying th ...
. North of Humboldt Hill, the road enters the City of Eureka (a potential new freeway cutting through or bypass of the city was successfully blocked repeatedly). As the route traverses Eureka, the southern portion is known as "Broadway" and then as it bears east along Humboldt Bay, the Highway is aligned on a one-way couplet (4th and 5th streets). later the highway leaves Eureka's northern city limit and continues north. The expressway style section between Eureka and
Arcata Arcata (; Wiyot: ''Goudi’ni''; Yurok: ''Oket'oh'') is a city adjacent to the Arcata Bay (northern) portion of Humboldt Bay in Humboldt County, California, United States. At the 2020 census, Arcata's population was 18,857. Arcata was first ...
, which is also a safety corridor, is named the "Michael J. Burns Freeway," in honor of the State Senator who was a proponent of California's Highways. The highway becomes an unobstructed freeway south of the center of Arcata. Proceeding north it passes the junction for SR 299 (also the western terminus for that route), in the Valley West (northernmost) part of the college town. The highway continues north as it skirts westerly around McKinleyville on a high bluff north of the Mad River. As the highway reaches Clam Beach (a county park), motorists get their first magnificent full view of the Pacific Ocean north of the Golden Gate. North of
Trinidad Trinidad is the larger and more populous of the two major islands of Trinidad and Tobago. The island lies off the northeastern coast of Venezuela and sits on the continental shelf of South America. It is often referred to as the southernmos ...
, the highway narrows to one lane in each direction after crossing Big Lagoon to pass inland of Stone Lagoon and follow the coastal bar between Freshwater Lagoon and the
Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contin ...
south of Orick. It becomes a undivided freeway through
Redwood National and State Parks The Redwood National and State Parks (RNSP) are a complex of one national park and three state parks, cooperatively managed, located in the United States along the coast of northern California. Comprising Redwood National Park (established 1968 ...
running inland east of the
Prairie Creek Redwoods State Park Prairie Creek Redwoods State Park is a state park, located in Humboldt County, California, near the town of Orick and 50 miles (80 km) north of Eureka. The 14,000 acre (57 km²) park is a coastal sanctuary for old-growth Coast Redw ...
boundary. The freeway narrows to one lane in each direction at the
Klamath River The Klamath River (Karuk: ''Ishkêesh'', Klamath: ''Koke'', Yurok: ''Hehlkeek 'We-Roy'') flows through Oregon and northern California in the United States, emptying into the Pacific Ocean. By average discharge, the Klamath is the second large ...
before losing its freeway designation in Klamath. The original placement of the highway near giant Coast Redwoods led to increased awareness of the destruction of the redwoods after decades of extensive logging, which ultimately led to the establishment of Redwood National Park in 1968. The original highway segment through Prairie Creek Redwoods State Park is now a scenic alternate similar to Avenue of the Giants, named Newton B. Drury Scenic Parkway in honor of the fourth director of the
National Park Service The National Park Service (NPS) is an agency of the United States federal government within the U.S. Department of the Interior that manages all national parks, most national monuments, and other natural, historical, and recreational propert ...
and executive director of the Save-the-Redwoods League North of the town of Klamath just inside Del Norte County, the highway closely follows the Pacific coast again. In Crescent City, US 101 once again separates into a one-way couplet (L and M Streets) for nine blocks. As it leaves Crescent City, US 101 becomes a divided freeway for the last time in California (built slightly to the west of the original two-lane alignment, now called Parkway Drive). As the 3-mile divided freeway portion ends, US 101 intersects the southern terminus of US 199, which heads northeast as the Redwood Highway, passing through the Collier Tunnel and terminating in Grants Pass, Oregon. US 101 (no longer called the "Redwood Highway" at this point) is reduced to two lanes and continues north along the California coast until it reaches the Oregon border.


Tolls


Express lanes

High-occupancy toll A high-occupancy toll lane (or HOT lane) is a type of traffic lane or roadway that is available to high-occupancy vehicles and other exempt vehicles without charge; other vehicles are required to pay a variable fee that is adjusted in response t ...
(HOT) lanes along US 101 between SR 237 in Mountain View and Whipple Avenue in
Redwood City Redwood City is a city on the San Francisco Peninsula in Northern California's Bay Area, approximately south of San Francisco, and northwest of San Jose. Redwood City's history spans its earliest inhabitation by the Ohlone people to being a po ...
opened on February 11, 2022. These express lanes are planned to be extended further north to
I-380 Interstate 380 may refer to: * Interstate 380 (California) Interstate 380 (I-380) is a short east–west auxiliary Interstate Highway in the San Francisco Bay Area of Northern California, connecting I-280 in San Bruno to US Route& ...
in
San Bruno San Bruno (Spanish for " St. Bruno") is a city in San Mateo County, California, United States, incorporated in 1914. The population was 43,908 at the 2020 United States Census. The city is between South San Francisco and Millbrae, adjacent to ...
, and south to I-880 in San Jose. , the HOT lanes' hours of operation is weekdays between 5:00 am and 8:00 pm. Solo drivers are tolled using a
congestion pricing Congestion pricing or congestion charges is a system of surcharging users of public goods that are subject to congestion through excess demand, such as through higher peak charges for use of bus services, electricity, metros, railways, tele ...
system based on the real-time levels of traffic. Two-person carpools and clean air vehicles with a solo driver are charged 50 percent of the posted toll. Carpools with three or more people and motorcycles are not charged. All tolls are collected using an
open road tolling Open road tolling (ORT), also called all-electronic tolling, cashless tolling, or free-flow tolling, is the collection of tolls on toll roads without the use of toll booths. An electronic toll collection system is usually used instead. The ma ...
system, and therefore there are no toll booths to receive cash. Each vehicle using the HOT lanes is required to carry either a
FasTrak FasTrak is the electronic toll collection (ETC) system used in the state of California in the United States. The system is used statewide on all of the toll roads, toll bridges, and high-occupancy toll lanes along the California Freeway an ...
''Flex'' or ''CAV'' (Clean Air Vehicle) transponder, with its switch set to indicate the number of the vehicle's occupants (1, 2, or 3 or more). Solo drivers may also use the FasTrak standard tag without the switch. Drivers without any FasTrak tag will be assessed a toll violation regardless of whether they qualified for free. The segment of the express lanes in Santa Clara County is co-administered by the
Santa Clara Valley Transportation Authority The Santa Clara Valley Transportation Authority, more commonly known simply as the Valley Transportation Authority (VTA), is a Special district (United States), special district responsible for public transit services, Congestion management agenc ...
(VTA) while the segment in San Mateo County is co-administered by the separate San Mateo County Express Lanes Joint Powers Authority, and so drivers will see separate toll charges when using each segment.


Golden Gate Bridge

Tolls are collected only for southbound traffic on the Golden Gate Bridge headed to San Francisco. An
open road tolling Open road tolling (ORT), also called all-electronic tolling, cashless tolling, or free-flow tolling, is the collection of tolls on toll roads without the use of toll booths. An electronic toll collection system is usually used instead. The ma ...
system is also used on the bridge, and they can be paid by either a
FasTrak FasTrak is the electronic toll collection (ETC) system used in the state of California in the United States. The system is used statewide on all of the toll roads, toll bridges, and high-occupancy toll lanes along the California Freeway an ...
transponder or license plate tolling. The
high-occupancy vehicle A high-occupancy vehicle lane (also known as an HOV lane, carpool lane, diamond lane, 2+ lane, and transit lane or T2 or T3 lanes) is a restricted traffic lane reserved for the exclusive use of vehicles with a driver and one or more passengers, i ...
(HOV) lane leading to the bridge requires a car with three or more people.


History


Juan Bautista de Anza National Historic Trail

The US 101 Highway is part of the auto tour route of the
Juan Bautista de Anza National Historic Trail The Juan Bautista de Anza National Historic Trail is a trail extending from Nogales on the U.S.-Mexico border in Arizona, through the California desert and coastal areas in Southern California and the Central Coast region to San Francisco. ...
, a
National Park Service The National Park Service (NPS) is an agency of the United States federal government within the U.S. Department of the Interior that manages all national parks, most national monuments, and other natural, historical, and recreational propert ...
unit in the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...
National Historic Trail The National Trails System is a series of trails in the United States designated "to promote the preservation of, public access to, travel within, and enjoyment and appreciation of the open-air, outdoor areas and historic resources of the Nati ...
and National Millennium Trail programs. In 2005, Caltrans began posting signs on roads that overlap with the historic 1776
Juan Bautista de Anza Juan Bautista de Anza Bezerra Nieto (July 6 or 7, 1736 – December 19, 1788) was an expeditionary leader, military officer, and politician primarily in California and New Mexico under the Spanish Empire. He is credited as one of the founding fa ...
trail route, so that California drivers can now follow the trail.


Historic route: San Diego to Los Angeles

Instead of terminating in Los Angeles, US 101 once continued all the way south through
San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the eighth most populous city in the United State ...
to the
United States–Mexico border United may refer to: Places * United, Pennsylvania, an unincorporated community * United, West Virginia, an unincorporated community Arts and entertainment Films * ''United'' (2003 film), a Norwegian film * ''United'' (2011 film), a BBC Two f ...
in San Ysidro. However, this part was decommissioned on July 1, 1964, in favor of
I-5 Interstate 5 (I-5) is the main north–south Interstate Highway on the West Coast of the United States, running largely parallel to the Pacific coast of the contiguous U.S. from Mexico to Canada. It travels through the states of Californi ...
. Though much of U.S. Route 101 has been superseded by I-5, several street segments of former Route 101 exist.


Historic route in San Diego County

Much of the route in northern San Diego County is County Route S21; this includes Coast Highway in Oceanside, Carlsbad Boulevard in Carlsbad, Coast Highway 101 in
Encinitas Encinitas (Spanish for "Small Oaks") is a beach city in the North County area of San Diego County, California. Located within Southern California, it is approximately north of San Diego, between Solana Beach and Carlsbad, and about south o ...
, Camino del Mar in
Del Mar Del Mar is Spanish for "of the sea" or "from the sea". It may refer to: Places in the United States * Del Mar, California * Del Mar High School, located in San Jose, California * Del Mar racetrack, located in Del Mar, California * Del Mar Fai ...
, and Torrey Pines Road in Torrey Pines. In San Diego, one alignment entered La Jolla Village on La Jolla Blvd, while a newer alignment went through Rose Canyon under what is now I-5. Roads followed by US-101 in San Diego included Mission Bay Drive, Pacific Hwy, Harbor Drive and Main Street. It ran along National City Blvd in National City, Broadway in
Chula Vista Chula Vista (; ) is the second-largest city in the San Diego metropolitan area, the seventh largest city in Southern California, the fifteenth largest city in the state of California, and the 78th-largest city in the United States. The popu ...
and Beyer Blvd in San Ysidro.


Oceanside–Carlsbad freeway bypass

By the early 1950s, traffic had become very heavy on US 101 through Oceanside and Carlsbad. The US 101 freeway bypass (Oceanside-Carlsbad freeway bypass) was built in 1953 and completed in 1955 by the California Department of Public Works (now Caltrans) and brought up by the San Diego Highway Development Association on a US 80/US 101 discussion on how to resolve the huge traffic loads on US 101 in Oceanside. Today it is part of I-5 and Palomar Airport Road. It follows I-5 from Coast Highway (former Hill Street exit) in Oceanside to Palomar Airport Road in Carlsbad. From there the US 101 bypass went onto Palomar Airport Road to merge with US 101 Bus. on Carlsbad Boulevard. As it approached the Coast Highway/SR 76 exit on southbound I-5 in Oceanside, US 101 Bus. split off. US 101 Bus. followed the original US 101 through downtown Oceanside and Carlsbad as former Hill Street/Carlsbad Boulevard (CR S-21) while the US 101 freeway followed modern I-5 and Palomar Airport Road. The south end of the freeway bypass is Carlsbad Boulevard and Palomar Airport Road and the north end is I-5 and the Coast Highway/SR 76 exit. The south end was modified after US 101 was decommissioned between the East Los Angeles Interchange in Los Angeles and the Mexican border in San Ysidro. This freeway construction by the California Department of Public Works put US 101 on an all new highway route alignment to relieve Oceanside and Carlsbad of their very heavy bumper-to-bumper burdensome traffic problem. Also before the bypass in the 1950s, US 101 followed North Coast Highway (formerly Hill Street) from San Luis Rey Mission Expressway (SR 76 and north end of the Oceanside–Carlsbad freeway bypass) to Harbor Drive. From there it followed Harbor Drive to Vandergrift Boulevard, San Rafael Drive, and the freeway onramp for I-5 north near the Camp Pendleton north entrance guardhouse gate. It merges with the I-5 northbound onramp to shoot onto the southbound lanes of I-5 to follow the freeway lanes all the way to Las Pulgas Road in Camp Pendleton.


Historic route in Orange and Los Angeles Counties

An old orphaned alignment of US 101, that ran through the cities of Mission Viejo, Laguna Niguel, San Juan Capistrano, Dana Point, and San Clemente, was located in south Orange County. The old roadway, from a dead end just west of I-5 and east of the railroad tracks in Mission Viejo to Cristianitos Road in San Clemente, followed Camino Capistrano, Doheny Park Road, Coast Highway and El Camino Real. It had interchanges with I-5 and California State Route 1. It was replaced by the San Diego freeway (which US 101 became part of it in 1958) and finally replaced by I-5 in 1968. In northern Orange County, US 101 followed
Harbor Boulevard Harbor Boulevard (formerly Spadra Road) is a north–south road corridor in the counties of Los Angeles and Orange. One of the busiest routes in Orange County, the thoroughfare passes through some of the most densely populated areas in the region ...
. U.S. Route 101 left Orange County, traversed southeast Los Angeles County, and entered the City of Los Angeles along
Whittier Boulevard Whittier Boulevard known as Stephenson Avenue (before 1920) is an arterial street that runs from the Los Angeles River (where it continues into Downtown Los Angeles as 6th Street) to Brea, California. The street is one of the main thoroughfares i ...
.


El Camino Real: Los Angeles to San Francisco

Significant portions of US 101 from its southern terminus to the San Francisco Bay Area is designated as the Royal Road or El Camino Real. The route roughly follows the historic trail that connected the former Alta California's 21 missions. Before the Golden Gate Bridge was completed in 1937, there was regular vehicle ferry service across the
Golden Gate The Golden Gate is a strait on the west coast of North America that connects San Francisco Bay to the Pacific Ocean. It is defined by the headlands of the San Francisco Peninsula and the Marin Peninsula, and, since 1937, has been spanned by t ...
strait, running from the Hyde Street Pier to Sausalito. Under the California Streets and Highways Code § 401, the Golden Gate Bridge is legally ''not'' part of US 101. The portion of US 101 starting from Los Angeles ends at "the approach to the Golden Gate Bridge" and then resumes at "a point in Marin County opposite San Francisco" to the Oregon state line. The bridge itself is maintained by the
Golden Gate Bridge, Highway and Transportation District The Golden Gate Bridge, Highway and Transportation District is a special-purpose district that owns and operates three regional transportation assets in the San Francisco Bay Area: the iconic Golden Gate Bridge, the Golden Gate Ferry system and ...
instead of Caltrans. From the 1940s to 1991, various segments of US 101 between Los Angeles and San Francisco were upgraded to either a freeway or expressway. In the Los Angeles area, the first segment of the
Hollywood Freeway The Hollywood Freeway is one of the principal freeways of Los Angeles, California (the boundaries of which it does not leave) and one of the busiest in the United States. It is the principal route through the Cahuenga Pass, the primary shortcut ...
through the Cahuenga Pass opened in 1940, while the segment from the San Fernando Valley to Downtown Los Angeles opened in 1954, replacing Cahuenga Boulevard. The
Ventura Freeway The Ventura Freeway is a freeway in southern California, United States, running from the Santa Barbara/ Ventura county line to Pasadena in Los Angeles County. It is the principal east-west route (designated north-south) through Ventura Count ...
then opened in 1960, replacing
Ventura Boulevard Ventura Boulevard is one of the primary east–west thoroughfares in the San Fernando Valley region of the City of Los Angeles, California. Ventura Boulevard is one of the oldest routes in the San Fernando Valley as it was originally a part o ...
. The segment of the original two-lane alignment between
Emma Wood State Beach Emma Wood State Beach is a California State Beach in Ventura, California. It is located on the Santa Barbara Channel on the west side of the Ventura River estuary and south of the railroad tracks of the Coast Line and the US Highway 101 freewa ...
north to the Mobil Pier Undercrossing near
Sea Cliff Seacliff or Sea Cliff or Sea Cliffe may refer to: ;Places ''Australia'' *Seacliff, South Australia, suburb of Adelaide * Seacliff Park, South Australia, a suburb of Adelaide *Sea Cliff Bridge, in Illawarra, New South Wales ''New Zealand'' *Seacl ...
, which followed the historic
Rincon Sea Level Road The Rincon Parkway is a portion of California State Route 1 along the north coast of Ventura County, California. This narrow coastal area north of the city of Ventura and south of the Santa Barbara County line is commonly referred to as The Ri ...
, was the re-signed as part of SR 1. In the San Francisco Bay Area, US 101 was originally divided. US 101W followed the same general
right-of-way Right of way is the legal right, established by grant from a landowner or long usage (i.e. by prescription), to pass along a specific route through property belonging to another. A similar ''right of access'' also exists on land held by a gov ...
of today's US 101 through the region, primarily along what was originally signed as Bayshore Boulevard. US 101E then generally followed the right-of-way taken by today's I-880 from San Jose to Oakland, then across the Carquinez Bridge to follow what is now SR 37, joining US 101W. The US 101E designation was removed by the 1940s and became SR 17 (later designated as I-880 and the westernmost section I-580), running from San Jose to Oakland and then across the
Richmond–San Rafael Bridge The Richmond–San Rafael Bridge (also officially named the John F. McCarthy Memorial Bridge) is the northernmost of the east–west crossings of the San Francisco Bay in California, USA. Officially named after California State Senator John ...
. Meanwhile, Bayshore Boulevard was later redesignated as the US 101A bypass and then eventually upgraded to what is now the Bayshore Freeway. The first stretch that was completed between Redwood City and South San Francisco was the Bay Area's first freeway when it opened in 1947. After the entire Bayshore Freeway was completed in the early 1960s, the old alignment along the peninsula was renumbered and renamed as SR 82/El Camino Real. Various other freeway or expressway bypasses along the
California Central Coast The Central Coast is an area of California, roughly spanning the coastal region between Point Mugu and Monterey Bay. It lies northwest of Los Angeles County and south of San Mateo and Santa Clara counties, and includes the rugged, undeveloped ...
were also built. In 1991, the last traffic signal along US 101 between Los Angeles and San Francisco was taken down in Santa Barbara. The primary
control city A control city is a city, locality, or other location posted on a series of traffic signs along a particular stretch of road indicating destinations on that route. Together with route numbers and cardinal directions, these focal points aid the m ...
that is listed on freeway signs along northbound US 101 through the Central Coast region remains San Francisco. As the result of
freeway revolt Highway revolts (also freeway revolts, expressway revolts, or road protests) are organized protests against the planning or construction of highways, freeways, expressways, and other civil engineering projects that favor vehicles. Many freeway r ...
s in San Francisco in the 1950s, a direct freeway connection through the city to the Golden Gate Bridge has never been built. The
Central Freeway The Central Freeway is a roughly one-mile (1.5 km) elevated freeway in San Francisco, California, United States, connecting the Bayshore/James Lick Freeway (US 101 and I-80) with the Hayes Valley neighborhood. Most of the freeway is part ...
was completed to extend from the Bayshore Freeway to Turk Street in 1959, before the San Francisco Board of Supervisors voted to remove the remainder of the Central Freeway and most other proposed freeways from the city's highway plan. For decades, southbound traffic on US 101 flowed on the one-way Turk Street from Van Ness Avenue to the Central Freeway, while northbound traffic used the parallel Golden Gate Avenue. After the 1989 Loma Prieta earthquake damaged the structure, the segment of the Central Freeway north of
Market Street Market Street may refer to: *Market Street, Cambridge, England *Market Street, Fremantle, Western Australia, Australia * Market Street, George Town, Penang, Malaysia *Market Street, Manchester, England *Market Street, Melbourne, Victoria, Australia ...
was replaced with the surface-level
Octavia Boulevard Octavia Boulevard (designated as Octavia Street north of Hayes Street) is a major street in San Francisco, California that replaced the Hayes Valley portion of the damaged two-level Central Freeway. Once a portion of Octavia Street alongside sh ...
; traffic on US 101 was then eventually re-routed to exit south of that at Mission Street/South Van Ness Avenue. With no direct freeway along US 101 through the City of San Francisco, the old US 101E/I-880/I-580 route remains as a faster bypass through the Bay Area. In the wake of the dot-com bubble expansion, the segment of US 101 between
Morgan Hill Morgan Hill is a city in Santa Clara County, California, at the southern tip of Silicon Valley, in the San Francisco Bay Area. Morgan Hill is an affluent residential community, the seat of several high-tech companies, and a dining, entertainmen ...
and San Jose, also known as the Sig Sanchez Freeway, expanded to eight lanes between Cochrane Road and SR 85 exits between 2001 and 2003 and a new interchange at Bailey Avenue, which had been planned since the 1970s, opened in 2004. Originally, the ten-mile segment was only four lanes (it was planned to have six lanes when opened in 1984). The improved segment was to alleviate the consistent congestion that had expanded as far south as Masten Avenue coming from Gilroy, and as far north as Bernal Road coming from San Jose. Traffic now typically only runs slow between the Bailey Avenue and East Dunne Avenue exits. The interchange at the beginning of I-280 and I-680 in San Jose was constructed years before its completion. The three flyovers, with no on ramps or off ramps connecting them stood at over US 101 for years in the 1970s (the SR 87/I-280 interchange also had this at the same time). It became the butt of many local jokes. The highlight prank occurred in January 1976, when a
1960 Chevrolet Impala The Chevrolet Impala () is a full-size car built by Chevrolet for model years 1958 to 1985, 1994 to 1996, and 2000 to 2020. The Impala was Chevrolet's popular flagship passenger car and was among the better-selling American-made automobiles in ...
was placed on the highest bridge overnight, where it obviously would be impossible to drive. The following day, San Jose City Councilman Joe Colla was photographed standing next to the car, a photo which was circulated across many newspapers. It has been suggested this stunt nudged the wheels of progress to find the funds to complete the freeway. In 2010, the interchange was named the Joe Colla Interchange.


Redwood Highway: Marin County to Del Norte County

An abandoned segment of the Redwood Highway, US 101, located in the
Redwood National and State Parks The Redwood National and State Parks (RNSP) are a complex of one national park and three state parks, cooperatively managed, located in the United States along the coast of northern California. Comprising Redwood National Park (established 1968 ...
near Klamath was added to the
National Register of Historic Places The National Register of Historic Places (NRHP) is the United States federal government's official list of districts, sites, buildings, structures and objects deemed worthy of preservation for their historical significance or "great artistic ...
in 1979. Freeway segments along the Redwood Highway portion of US 101 are not as prevalent as along the Los Angeles-San Francisco route. A notable segment of the old US 101 alignment is SR 254, also known as the
Avenue of the Giants The Avenue of the Giants is a scenic highway in northern California, United States, running through Humboldt Redwoods State Park. It is named after the coastal redwoods that tower over the route. The road is a former alignment of U.S. Route 101, ...
, in Humboldt Redwoods State Park. The freeway bypassing this scenic route, surrounded by towering
Coast Redwood ''Sequoia sempervirens'' ()''Sunset Western Garden Book,'' 1995:606–607 is the sole living species of the genus '' Sequoia'' in the cypress family Cupressaceae (formerly treated in Taxodiaceae). Common names include coast redwood, coastal ...
s, was completed in 1960. Several bridges along the segment of highway running along the Eel River were destroyed during the
Christmas flood of 1964 The Christmas flood of 1964 was a major flood in the United States' Pacific Northwest and some of Northern California between December 18, 1964, and January 7, 1965, spanning the Christmas holiday. Considered a 100-year flood, it was the wor ...
. Construction on a freeway segment bypassing Willits began in 2013. The bypass around Willits remained controversial because the intended route goes through protected wetlands. Construction was halted by US Army Corps of Engineers in June 2014 and work restarted the following month after Caltrans committed to extensive mitigation of the project. The bypass around Willits opened to traffic in November 2016. The bypass included a viaduct going over a flood plain. The freeway segment cost $459 million to complete, 50% more than what Caltrans first reported when it opened. The city of Eureka has long resisted a freeway through it.


Future

The proposed Wallis Annenberg Wildlife Crossing is a vegetated overpass spanning the
Ventura Freeway The Ventura Freeway is a freeway in southern California, United States, running from the Santa Barbara/ Ventura county line to Pasadena in Los Angeles County. It is the principal east-west route (designated north-south) through Ventura Count ...
and Agoura Road at Liberty Canyon in
Agoura Hills Agoura Hills () is a city in the Santa Monica Mountains region of Los Angeles County, California, United States. Its population was 20,330 at the 2010 census, which decreased to 20,299 in 2020. It is in the eastern Conejo Valley between the S ...
. If built, it will be one of the largest urban
wildlife crossing Wildlife crossings are structures that allow animals to cross human-made barriers safely. Wildlife crossings may include underpass tunnels or wildlife tunnels, viaducts, and overpasses or green bridges (mainly for large or herd-type animals); a ...
s in the United States, connecting the
Simi Hills The Simi Hills are a low rocky mountain range of the Transverse Ranges in eastern Ventura County and western Los Angeles County, of southern California, United States. Geography The Simi Hills are aligned east-west and run for , and average aro ...
and the
Santa Monica Mountains The Santa Monica Mountains is a coastal mountain range in Southern California, next to the Pacific Ocean. It is part of the Transverse Ranges. Because of its proximity to densely populated regions, it is one of the most visited natural areas in ...
over a busy freeway with ten traffic lanes (including exit lanes). The Richardson Grove section of US 101 has been proposed for a bypass for many years, but Caltrans conducted a study in 2000 which stated that a bypass was not cost effective and recommended realignment of US 101 within the redwood grove instead to accommodate modern-sized trucks in compliance with the Surface Transportation Assistance Act (STAA).


Major intersections


See also

* *


References


External links


Bay Area FasTrak
– includes toll information on the US 101 Express Lanes, the Golden Gate Bridge and the other Bay Area toll facilities
Drive the 101: historical information websiteCaltrans: Route 101 highway conditions
{{DEFAULTSORT:U.S. Route 101 In California 01-1 101 Roads on the National Register of Historic Places in California 101 U.S. Route A101 U.S. Route A101 U.S. Route A101 U.S. Route A101 U.S. Route A101 U.S. Route A101 U.S. Route A101 U.S. Route A101 U.S. Route A101 U.S. Route A101 U.S. Route A101 U.S. Route A101 U.S. Route A101 U.S. Route A101 101 101 California National Register of Historic Places in Del Norte County, California National Register of Historic Places in Redwood National and State Parks