U.S. Route 51 (US 51) in the U.S. state of

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 Rockf ...

, is a main north–south artery that runs from the

Ohio River The Ohio River is a long river in the United States. It is located at the boundary of the Midwestern and Southern United States, flowing southwesterly from western Pennsylvania to its mouth on the Mississippi River at the southern tip of Illi ...

north to the

Wisconsin Wisconsin () is a state in the upper Midwestern United States. Wisconsin is the 25th-largest state by total area and the 20th-most populous. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michi ...

border, a distance of .

Route description

US 51 enters Illinois from Kentucky at the city town of

Cairo, Illinois Cairo ( ) is the southernmost city in Illinois and the county seat of Alexander County. The city is located at the confluence of the Ohio and Mississippi rivers. Fort Defiance, a Civil War camp, was built here in 1862 by Union General Ul ...

. The highway heads northbound to a village near Cairo called Mounds, and begins to overlap

Interstate 57 Interstate 57 (I-57) is a north–south Interstate Highway in Missouri and Illinois that parallels the old Illinois Central Railroad for much of its route. It runs from Sikeston, Missouri, at I-55 to Chicago, Illinois, at I-94. I-57 ess ...

(I-57), following it for to

Dongola Dongola ( ar, دنقلا, Dunqulā), also spelled ''Dunqulah'', is the capital of the state of Northern Sudan, on the banks of the Nile, and a former Latin Catholic bishopric (14th century). It should not be confused with Old Dongola, an ancie ...

, before splitting and heading north. The highway remains two lanes wide from Dongola to Assumption with the exception of a section between Centralia and

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 ...

. Past Assumption, US 51 becomes an expressway to Decatur. In Decatur, US 51 follows

I-72 Interstate 72 (I-72) is an Interstate Highway in the midwestern United States. Its western terminus is in Hannibal, Missouri, at an intersection with U.S. Route 61 (US 61); its eastern terminus is at Country Fair Drive in Champai ...

to bypass the city. US 51 leaves I-72 after , and it heads north to Bloomington– Normal as an expressway. At Bloomington–Normal, US 51 follows

I-74 } Interstate 74 (I-74) is an Interstate Highway in the Midwestern and Southeastern United States. Its western end is at an interchange with I-80 in Davenport, Iowa (Quad Cities); the eastern end of its Midwest segment is at an interchange ...

for a mile, then

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 ...

for , before following

I-39 Interstate 39 (I-39) is a highway in the Midwestern United States. I-39 runs from Normal, Illinois, at I-55 to State Trunk Highway 29 (WIS 29) in the town of Rib Mountain, Wisconsin, which is approximately south of Wausau. I- ...

for . US 51 follows I-39, intersecting

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

I-88 Interstate 88 may refer to either of two United States Interstate highways: * Interstate 88 (Illinois), running from East Moline to Hillside * Interstate 88 (New York) Interstate 88 (I-88) is an Interstate Highway located entirely with ...

along the way. The highway also follows US 20 south of Rockford (while still following I-39). I-39/US-51 join

I-90 Interstate 90 (I-90) is an east–west transcontinental freeway and the longest Interstate Highway in the United States at . It begins in Seattle, Washington, and travels through the Pacific Northwest, Mountain West, Great Plains, Midwest, an ...

, making US 51 one of the few toll highways in Illinois that is a U.S. Highway. US 51 exits I-39/I-90 just a mile south of the Wisconsin state line. Then US 51 follows

Illinois Route 75 Illinois Route 75 (IL 75) is an east–west state highway in north-central Illinois. It runs from downtown Freeport at Illinois Route 26 to WIS 67 at the Wisconsin state line southeast of Beloit, Wisconsin. This is a distance of . Route d ...

(IL 75) west to the intersection of IL 251, and then turns north through

South Beloit, Illinois South Beloit, is a city located in Winnebago County, Illinois, USA. It is part of the Rockford Metropolitan Area, but it is also a suburban extension of Beloit, Wisconsin. South Beloit,is directly along the border of smaller cities and towns nort ...

to enter Wisconsin.

History

US 51 was established in Illinois in the 1920s. Over the years, it became a heavily traveled highway, often experiencing many accidents, particularly in the northern half of the state. This highway gained the moniker of "Killer 51". As a result of these problems, Illinois pushed for a new four lane highway along the corridor. One was proposed in the 1960s and 1970s as part of a proposed supplemental freeway system, but only the area between Rockford and Decatur was given a high priority. In the 1980s and early 1990s, US 51 was rebuilt to

Interstate standards Standards for Interstate Highways in the United States are defined by the American Association of State Highway and Transportation Officials (AASHTO) in the publication ''A Policy on Design Standards: Interstate System''. For a certain highway t ...

between Rockford and Bloomington– Normal on a new alignment. This new highway became

Interstate 39 Interstate 39 (I-39) is a highway in the Midwestern United States. I-39 runs from Normal, Illinois, at I-55 to State Trunk Highway 29 (WIS 29) in the town of Rib Mountain, Wisconsin, which is approximately south of Wausau. ...

, and US 51 was rerouted onto it. In addition, north of Rockford, US 51 was rerouted onto the existing

segment between South Beloit and Cherry Valley. Most of the old highway became IL 251. South of Bloomington–Normal to Decatur, US 51 remained largely on the original alignment, and it was expanded to an expressway. In the 2000s, the expressway was continued southward from Decatur to

Assumption, Illinois Assumption is a city in Christian County, Illinois, United States. The population was 1,155 as of the 2020 census. History Assumption originally was called "Tacusah". The present name is after Assumption Parish, Louisiana. A post office called ...

Major intersections

References

External links