U.S. Route 51 in Illinois

U.S. Route 51
Route information
	Maintained by IDOT
Length:	415.95 mi (669.41 km); Length may include both directions of route where it is routed along one-way streets.
Major junctions
South end:	US 51 / US 60 / US 62 near Wickliffe, KY
	I-57 near Cairo; I-64 near Richview; I-70 at Vandalia; I-72 at Decatur; I-39 / I-55 / I-74 at Bloomington/Normal; I-80 at La Salle; I-88 at Rochelle; I-90 at Rockford; I-39 / I-90 at South Beloit
North end:	US 51 at the Wisconsin state line in South Beloit
Highway system

U.S. Route 51 (US 51) in the U.S. state of Illinois, is a main north–south artery that runs from the Ohio River north to the Wisconsin border, a distance of 415.95 miles (669.41 km).^[1]

Route description

U.S. Route 51 enters Illinois from Kentucky at the town of Cairo. The route heads northbound to a village near Cairo called Mounds, and begins to overlap I-57, following it for 24 miles (39 km) to Dongola, before splitting and heading north. The route remains two lanes from Dongola to Assumption with the exception of a 10-mile (16 km) section between Centralia and I-64.

Past Assumption, US 51 becomes an expressway to Decatur. In Decatur, US 51 follows I-72 to bypass town. US 51 leaves I-72 after eight miles (13 km), and heads north to Bloomington–Normal as an expressway. At Bloomington–Normal, US 51 follows I-74 for a mile, then I-55 for seven miles (11 km), before following I-39 for 140 miles (230 km).

US 51 follows I-39, intersecting I-80 and I-88 along the way. The highway also follows US 20 south of Rockford (while still following I-39). I-39/US 51 joins I-90, making US 51 of the only toll roads in Illinois that is a U.S. Highway. US 51 exits I-39/I-90 just a mile south of the Wisconsin state line. US 51 follows Illinois Route 75 (IL 75) west to the intersection of IL 251, then turns north through South Beloit to enter Wisconsin.

History

US 51 was established in Illinois in the 1920s. Over the years, it became a heavily traveled road, often experiencing many accidents, particularly in the northern half of the state. The road gained the reputation "Killer 51". As a result of these impacts, 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 prioritized.^[2]

In the 1980s and early 1990s, US 51 was built to Interstate Highway standards between Rockford and Bloomington–Normal on a new alignment. This new road became Interstate 39, and US 51 was re-routed onto the new highway. Additionally, north of Rockford, it was re-routed onto the existing Interstate 90 tollway segment between South Beloit and Cherry Valley. Most of the old alignment became Illinois Route 251.

South of Bloomington–Normal to Decatur, US 51 remained largely on the original alignment and was expanded to an expressway, despite a push to continue building to Interstate Highway standards.^[3] Further continuation of the expressway occurred in the 2000s, when the highway was upgraded south to Assumption.

Future

Plans are underway to continue the US 51 expressway south of Assumption to Centralia.^[4] An environmental impact statement is currently being prepared. However, construction funding remains elusive.

Major intersections

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County	Location	Exit	Destinations	Notes
Alexander	Cairo		US 51 south / US 60 east / US 62 east – Wickliffe	US 51/US 60/US 62 continue into Kentucky
			US 60 west / US 62 west – Charleston	Northern end of US 60/US 62 concurrency
			IL 37 north – Mound City	Southern terminus of IL 37
		1	I-57 south / IL 3 north – Olive Branch, Memphis	Southern end of I-57 concurrency; southern terminus of IL 3
Pulaski		8	Mounds Road
Pulaski		18	Ullin Road
Union	Dongola	24	Dongola Road
	Dongola	25	I-57 north – Chicago	Northern end of I-57 concurrency; northbound exit and southbound entrance
	Anna		IL 146 – Jonesboro, Vienna
Jackson	Carbondale		IL 13 – Murphysboro, Marion
Jackson	De Soto		IL 149 – Murphysboro, Hurst
Perry	Du Quoin		IL 14 east – Christopher	Western terminus of IL 14
	Du Quoin		IL 152 west – Pyatts	Eastern terminus of IL 152
	Sunfield		IL 154 – Red Bud, Sesser
Washington	Ashley		IL 15 west – East St. Louis	Western end of IL 15 concurrency
	Ashley		IL 15 east – Mount Vernon	Eastern end of IL 15 concurrency
	Richview		I-64 – St. Louis, Louisville	Exit 61 on I-64
	Irvington		IL 177 west – Belleville	Western terminus of IL 177
Marion	Centralia		IL 161 – New Baden, Kell
	Sandoval		US 50 west – Carlyle	Western end of US 50 concurrency
	Sandoval		US 50 east – Salem	Eastern end of US 50 concurrency
Fayette	Vandalia		US 40 east / IL 185 east – Bluff City	Eastern end of US 40/IL 185 concurrency
			US 40 west / IL 185 west – Taylor Springs, Mulberry Grove	Western end of US 40/IL 185 concurrency
			I-70 – St. Louis, Indianapolis	Exit 63 on I-70
Christian	Pana		IL 16 west	Western end of IL 16 concurrency
	Pana		IL 29 north	Southern terminus of IL 29
			IL 16 east	Eastern end of IL 16 concurrency
Macon			US 51 Bus. north
			IL 48
	Harristown	133	I-72 west / US 36 – Springfield, Tuscola	Southern end of I-72 concurrency; signed as exits 133A (east) and 133B (south)
	Decatur	138	IL 121 – Decatur, Lincoln
	Decatur	141	I-72 east / US 51 Bus. south – Champaign, Urbana, Decatur
DeWitt	Clinton		US 51 Bus. north – Clinton
			IL 54
			IL 10
			US 51 Bus. south – Clinton
McLean	Heyworth		US 136 – McLean, Rantoul
		135	I-74 east / US 51 Bus. north (Main Street) – Indianapolis, Bloomington	Southern end of I-74 concurrency
		157A	I-55 south – St. Louis	Southern end of I-55 concurrency
	Bloomington	157B	I-55 Bus. north (Veterans Parkway)	Signed as exit 134B (north) southbound
	Bloomington	160	US 150 / IL 9 (Market Street) – Pekin
		163	I-74 west – Peoria	Northern end of I-74 concurrency
		164	I-39 north / I-55 north – Chicago	Northern end of I-55 concurrency; southern end of I-39 concurrency; southern terminus of I-39
		2	US 51 Bus. south – Bloomington, Normal
	Hudson	5	Hudson
		8	IL 251 (Lake Bloomington Road)
Woodford	El Paso	14	US 24 – El Paso, Peoria
	Woodford	22	IL 116 – Peoria, Pontiac
	Minonk	27	Minonk
Marshall	Wenona	35	IL 17 – Lacon, Wenona
LaSalle	Lostant	41	IL 18 – Henry, Streator
	Tonica	48	Tonica
		51	IL 71 – Hennepin, Oglesby
		52	IL 251 – Peru, LaSalle
	Oglesby	54	Oglesby
	Illinois River	Abraham Lincoln Memorial Bridge
	La Salle	57	US 6 – LaSalle, Peru, Ottawa
		59	I-80 – LaSalle, Peru, Chicago, Des Moines	Signed as exits 59A (east) and 59B (west)
	Troy Grove	66	US 52 – Troy Grove
	Mendota	72	US 34 – Mendota, Earlville
Lee	Paw Paw	82	Paw Paw
		87	US 30 – Sterling, Rock Falls, Aurora
	Steward	93	Steward
Ogle	Rochelle	97	I-88 / IL 110 (Ronald Reagan Memorial Tollway) – Moline, Rock Island, Chicago	Signed as exits 97A (east) and 97B (west)
	Rochelle	99	IL 38 – DeKalb, Rochelle
		104	IL 64 – Sycamore, Oregon
	Monroe Center	111	IL 72 – Genoa, Byron
Winnebago		115	Baxter Road
	Rockford		US 20 west – Freeport, Rockford	Southern end of US 20 concurrency, I-39/US 51 southbound exits US 20 via exit 97
	Cherry Valley	122A	US 20 east – Belvidere	Northern end of US 20 concurrency
		122B	Harrison Avenue
		17	I-90 east (Jane Addams Memorial Tollway) – Chicago	Southern end of I-90 concurrency; I-39/US 51 uses I-90's exit numbers from here north
	Rockford	15	US 20 Bus. (State Street)	Last free exit northbound
	Rockford	12	Riverside Boulevard	Toll on northbound exit and southbound entrance
	Machesney Park	9	IL 173 (West Lane Road)	Toll on northbound exit and southbound entrance
	Rockton	South Beloit Toll Plaza
	South Beloit	3	Rockton Road (CR 9)	Last free exit southbound
		1	I-39 north / I-90 west / IL 75 east – South Beloit, Madison	Northern end of I-39/I-90 concurrency; eastern end of IL 75 concurrency
			IL 75 west / IL 251 south – Freeport, Rockford	Western end of IL 75 concurrency; northern terminus of IL 251
			US 51 north – Beloit	Continuation into Wisconsin
1.000 mi = 1.609 km; 1.000 km = 0.621 mi Concurrency terminus Tolled