Interstate 270 (I-270) makes up a large portion of the outer belt

freeway A controlled-access highway is a type of highway that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway, motorway and expressway. Other similar terms i ...

Greater St. Louis Greater St. Louis is a bi-state metropolitan area that completely surrounds and includes the independent city of St. Louis, the principal city. It includes parts of both Missouri and Illinois. The city core is on the Mississippi Riverfront on t ...

. The counterclockwise terminus of I-270 is at the junction with

I-55 Interstate 55 (I-55) is a major Interstate Highway in the central United States. As with most primary Interstates that end in a five, it is a major cross-country, north–south route, connecting the Gulf of Mexico to the Great Lakes. The h ...

and

I-255 Interstate 255 (I-255) is a bypass route of I-55 in Greater St. Louis. Along with I-270, it forms a loop around the central portion of the bi-state metro area; a majority of I-255 is located on the Illinois half. It shares its southern ...

Mehlville, Missouri Mehlville is a census-designated place (CDP) in south St. Louis County, Missouri, United States, an area locally known as "South County". It is an inner-ring suburb of St. Louis, and part of the Greater St. Louis metropolitan area. The populatio ...

; the clockwise terminus of the freeway is at the junction with I-55 and

I-70 Interstate 70 (I-70) is a major east–west Interstate Highway in the United States that runs from I-15 near Cove Fort, Utah, to a park and ride lot just east of I-695 in Baltimore, Maryland, and is the fifth-longest Interstate in the c ...

north of

Troy, Illinois ''For the village in Will County, see Shorewood, Illinois.'' Troy is a city in Madison County, Illinois, United States. The population was 10,960 at the 2020 census. Troy is part of the St. Louis Metropolitan Statistical Area. Its namesake in Li ...

. The entire stretch of I-270 is . I-270 between I-70 and I-55 was formerly designated I-244, a western bypass of

St. Louis, Missouri St. Louis () is the second-largest city in Missouri, United States. It sits near the confluence of the Mississippi and the Missouri Rivers. In 2020, the city proper had a population of 301,578, while the bi-state metropolitan area, which e ...

. It was originally proposed by Missouri as I-144, but the road was a beltway (or part of one), so the

American Association of State Highway and Transportation Officials The American Association of State Highway and Transportation Officials (AASHTO) is a standards setting body which publishes specifications, test protocols, and guidelines that are used in highway design and construction throughout the United S ...

(AASHTO) assigned it the number I-244. By the late 1970s, the entire beltway (including today's I-255) was integrated as a part of I-270 for consistency. However, the politicians in Illinois started planning their supplemental freeway system in the mid-1970s, and a section of Corridor 413 was included into the

Interstate Highway System The Dwight D. Eisenhower National System of Interstate and Defense Highways, commonly known as the Interstate Highway System, is a network of controlled-access highways that forms part of the National Highway System in the United States. Th ...

in April 1978. This caused a potential place of confusion in

Pontoon Beach, Illinois Pontoon Beach is a village in Madison County, Illinois, United States. The population was 5,836 at the 2010 census. Geography Pontoon Beach is located at (38.726078, -90.060505). According to the 2010 census, Pontoon Beach has a total area of , ...

, where I-270 would have intersected itself, and eventually the

Illinois Department of Transportation The Illinois Department of Transportation (IDOT) is a state agency in charge of state-maintained public roadways of the U.S. state of Illinois. In addition, IDOT provides funding for rail, public transit and airport projects and administers fuel ...

(IDOT) decided on the I-255 numbering in 1980 (but not before considering renumbering an section to I-870).

Route description

In Missouri, I-270 diverges from at

as a 10-lane freeway heading west of I-55's route but still maintaining a I-55's tendency to travel northward. I-270 intersects

I-44 Interstate 44 (I-44) is a major Interstate Highway in the central United States. Although it is nominally an east–west road as it is even-numbered, it follows a more southwest–northeast alignment. Its western terminus is in Wichita Fal ...

in a modified

cloverleaf interchange A cloverleaf interchange is a two-level interchange (road), interchange in which all turns are handled by slip roads. To go left (in right-hand traffic; reverse directions in left-driving regions), vehicles first continue as one road passes ...

that was rebuilt in the 1990s. Railroad overpasses and rocky bluffs between I-44 and Dougherty Ferry Road reduced the interstate to eight lanes for about ; however, this section was widened as of late 2013 to five lanes in each direction. I-270 meets up with

I-64 Interstate 64 (I-64) is an east–west Interstate Highway in the Eastern United States. Its western terminus is at I-70, U.S. Route 40 (US 40), and US 61 in Wentzville, Missouri. Its eastern terminus is at an interchange ...

with a

stack interchange A directional interchange, colloquially known as a stack interchange, is a type of Interchange (road), grade-separated junction between two controlled-access highways that allows for free-flowing movement to and from all directions of traffic. ...

that was built from 1987 to 1993 (it was previously a cloverleaf that was a frequent source of backups). Int270nRoad-Exit20AB-Int70ew (26908205188)

From Dougherty Ferry Road through

, it continues as a 10-lane Interstate, although the right lanes often serve as exit lanes. The intersection with Route 340 (Olive Boulevard) was upgraded to a

single-point urban interchange A single-point urban interchange (SPUI, or ), also called a single-point interchange (SPI) or single-point diamond interchange (SPDI), is a type of highway interchange. The design was created in order to help move large volumes of traffic thr ...

in the mid-2000s, and, during 2010–2011, the interchanges with Route 364 (Page Avenue) and Dorsett Road were upgraded with the latter becoming a

diverging diamond interchange A diverging diamond interchange (DDI), also called a double crossover diamond interchange (DCD), is a subset of diamond interchange in which the opposing directions of travel on the non-freeway road cross each other on either side of the inte ...

in October 2010. Congestion in this area is severe to the point the

Missouri Department of Transportation The Missouri Department of Transportation (MoDOT, ) is a state government organization in charge of maintaining public roadways of the U.S. state of Missouri under the guidance of the Missouri Highways and Transportation Commission. MoDOT designs, ...

(MoDOT) has spent millions on various traffic control improvements since the 1990s. One of the safety improvements is a "double white line" that motorists are not permitted to cross (violation of that could lead to a fine of $500) that is located at the exits for I-70 in the northbound lanes. Other safety implementations include a special Maryland Heights police cruiser that is dedicated to traffic enforcement on this section of I-270, congestion warning signs, and traffic cameras. At I-70, I-270 makes a transition from a north–south highway to an east–west highway though not signed as such until James S. McDonnell Boulevard and will eventually become a six-lane highway by the time it reaches U.S. Route 67 (US 67, North Lindbergh Boulevard). It then meets

I-170 Interstate 170 (I-170), also known as the Inner Belt Expressway, is an north–south Interstate Highway in Greater St. Louis, Missouri. I-170 connects to I-270 at its northern terminus and I-64 at its southern terminus. I-170 crosses it ...

, which had its interchange rebuilt from 2001 to 2004 during which a left exit lane in the westbound lane was corrected. This section of I-270 was a source of frequent backups during the late-afternoon hours until the interchange was rebuilt. A fatal accident in September 1999 spurred the rebuilding of the interchange, although the accident did not occur at that location happening east of the interchange. I-270 then passes various streets where every westbound exit connects to Dunn Road (and one must use Dunn Road to access I-270 with the only exceptions being the Route 367, Lilac Avenue, and Riverview Drive exits). Since Dunn Road handles two-way traffic, this has become a safety and congestion issue that MoDOT wants to address in the near future. At Lilac Avenue, I-270 constricts to four lanes as it crosses the

Mississippi River The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it fl ...

on the

New Chain of Rocks Bridge The New Chain of Rocks Bridge is a pair of bridges across the Mississippi River on the north edge of St. Louis, Missouri. It was constructed in 1966 to bypass the Chain of Rocks Bridge immediately to the south. It originally carried traffic f ...

s. Leaving Missouri and entering

Illinois Illinois ( ) is a state in the Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolitan areas include, Peoria and Rockfo ...

, I-270 transitions from a suburban Interstate to an

exurb An exurb (or alternately: exurban area) is an area outside the typically denser inner suburban area, at the edge of a metropolitan area, which has some economic and commuting connection to the metro area, low housing density, and growth. It sh ...

an Interstate with farm fields and wooded land bordering the Interstate in the area to the immediately east and west of the river crossing. Once it crosses the Chain of Rocks Canal, I-270 will intersect four different highways providing access to communities in eastern Madison County:

Illinois Route 3 Illinois Route 3 (IL 3) is a major north–south arterial state highway in southwestern Illinois. It has its southern terminus at Cairo Junction (about north of Cairo) at the intersection of U.S. Route 51 (US 51) and Illinois ...

(IL 3), Old Alton Road, IL 203, and IL 111. The interchange with IL 3 is a partial cloverleaf with the loop ramps in the northeast and southeast quadrants. The remaining two are cloverleaf interchanges, with the Old Alton Road/IL 203 interchange using a collector–distributor system with two folded diamonds due to the presence of railroad tracks between the two roadways. Once it passes IL 111, the speed limit increases to as the highway briefly becomes six lanes again with the junction with

. The highway then reverts to a four-lane highway offering diamond interchanges with IL 157 and IL 159 before meeting up with I-55/I-70 at the interchange that IDOT refers as the "3 I's". The eastbound I-270 meets the northeastbound combination of I-55 and I-70 which leave the intersection as northbound I-55 and eastbound I-70 which has adopted I-270's mile markings.

History

The section of I-270 on the Missouri side was completed by June 1964, while the section that was I-244 was completed by November 1968. The section from IL 3 to I-55 in Illinois was finished by May 1965. During the

Great Flood of 1993 The Great Flood of 1993 (or Great Mississippi and Missouri Rivers Flood of 1993) was a flood that occurred in the Midwestern United States, along the Mississippi and Missouri rivers and their tributaries, from April to October 1993. The flood wa ...

, the

carrying I-270 over the

was the only bridge open from St. Louis to

Keokuk, Iowa Keokuk is a city in and a county seat of Lee County, Iowa, United States, along with Fort Madison. It is Iowa's southernmost city. The population was 9,900 at the time of the 2020 census. The city is named after the Sauk chief Keokuk, who is ...

, at one point. (All other bridges from the

McKinley Bridge The McKinley Bridge is a steel truss bridge across the Mississippi River. It connects northern portions of the city of St. Louis, Missouri with Venice, Illinois. It opened in 1910 and was taken out of service on October 30, 2001. The bridge wa ...

to the Keokuk Bridge were closed at the peak of that flood.) The last major construction project on I-270 occurred from 1995 to 1998. Both MoDOT and IDOT upgraded I-270 to modern standards from Lilac Avenue to I-255. However, this section of I-270 is still at two lanes in each direction. On September 13, 1999, a fatal accident involving a tractor-trailer occurred in the westbound lanes of I-270 in front of the now-defunct St. Thomas Aquinas-Mercy High School (now North County Christian School) in northern St. Louis County. This accident sped up efforts that led to the I-170/I-270 interchange reconstruction that went from 2001 to 2004. A major accident and fire from a

FedEx Ground FedEx Ground, a subsidiary of the FedEx Corporation, is an American ground package delivery company headquartered in Moon Township, Pennsylvania, a suburb of Pittsburgh. The company began as Roadway Package System (RPS), founded in 1985 b ...

truck between the Route 367 and Lilac Avenue exits on October 28, 2002, forced detours and lengthy delays. There were plans to sign an section of I-270 from Glen Carbon to Edwardsville as I-870. However, this idea was discarded. In 2008, MoDOT implemented new variable speed limits on I-270/I-255 with the normal limit being . However, due to complaints from the public, these signs were planned to be updated in 2011 to advisory signs. A section of I-270 between I-44 and Manchester was widened to five lanes in each direction, with work taking place between 2012 and 2013. This section of I-270 sees up to 185,000 vehicles per day, and peak hour congestion is common.

Constructions

IDOT wanted to widen I-270 from Lilac Avenue to

from four lanes to six, but no money was available at the time of the proposal in 2007. However, IDOT has announced that nearly $100 million has been programmed for replacement of the canal bridges between 2011 and 2016. The canal bridges were replaced in mid-2014, and the old deck was imploded late 2015. MoDOT has also identified the need of improving the I-270 corridor in northern St. Louis County, which could cost in the range of $200 million. The agency planned to widen the freeway from US 67 to Route 367 and rebuild every interchange (except I-170) and overpasses in this section. MoDOT held a public study of this corridor and has a website of this. Construction eventually began in spring 2020 and is expected to conclude in December 2023 at a price of under $300 million.

Exit list

References

External links