U.S. Route 51 in Illinois

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]

U.S. Route 51
US 51 highlighted in red, IL 251 in blue
Route information
Maintained by IDOT and ISTHA
Length415.95 mi[1] (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
CountiesAlexander, Pulaski, Union, Jackson, Perry, Washington, Jefferson, Marion, Fayette, Shelby, Christian, Macon, DeWitt, McLean, Woodford, Marshall, LaSalle, Lee, Ogle, Winnebago
Highway system
IL 50US 52

Route description

US 51 enters Illinois from Kentucky at the city town of Cairo, Illinois. The highway heads northbound to a village near Cairo called Mounds, and begins to overlap Interstate 57 (I-57), following it for 24 miles (39 km) to Dongola, before splitting and heading north. The highway remains two lanes wide 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 the city. US 51 leaves I-72 after eight miles (13 km), and it heads north to BloomingtonNormal 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 join I-90, making US 51 one of the few toll highway 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 (IL 75) west to the intersection of IL 251, and then turns north through South Beloit, Illinois to enter Wisconsin.


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.[2]

In the 1980s and early 1990s, US 51 was rebuilt to Interstate Highway standards between Rockford and BloomingtonNormal on a new alignment. This new highway became Interstate 39, and US 51 was rerouted onto it. In addition, north of Rockford, US 51 was rerouted onto the existing I-90 tollway 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. Further continuation of the expressway occurred in the 2000s, when the highway was upgraded southward from Decatur to Assumption, Illinois.


Plans are underway to continue the US 51 expressway south of Assumption to Centralia.[3] An environmental impact statement is currently being prepared. However, construction funding remains elusive.

Major intersections

AlexanderCairo0.00.0 US 51 south / US 60 east / US 62 east WickliffeUS 51/US 60/US 62 continue into Kentucky
0.20.32 US 60 west / US 62 west to I-57 south CharlestonNorthern end of US 60/US 62 concurrency
4.57.2 IL 37 north / IL 3 begins Mound CitySouthern terminus of IL 37; southern terminus of IL 3; southern end of IL 3 concurrency
5.38.51 IL 3 north Olive Branch
I-57 south Sikeston, MO
Northern end of IL 3 concurrency; southern end of I-57 concurrency
Pulaski11.418.38Mounds Road
21.434.418Ullin Road
UnionDongola28.245.424Dongola Road
28.846.325 I-57 north ChicagoNorthern end of I-57 concurrency; northbound exit and southbound entrance
Anna36.057.9 IL 146 Jonesboro, Vienna
JacksonCarbondale55.088.5 IL 13 Murphysboro, Marion
De Soto61.398.7 IL 149 Murphysboro, Hurst
PerryDu Quoin72.4116.5 IL 14 east ChristopherWestern terminus of IL 14
75.5121.5 IL 152 west PyattsEastern terminus of IL 152
Sunfield80.4129.4 IL 154 Red Bud, Sesser
WashingtonAshley98.0157.7 IL 15 west East St. LouisWestern end of IL 15 concurrency
100.9162.4 IL 15 east Mount VernonEastern end of IL 15 concurrency
Richview105.7170.1 I-64 Mount Vernon, East St. LouisI-64 exit 61
Irvington109.6176.4 IL 177 west BellevilleWestern terminus of IL 177
No major junctions
MarionCentralia116.2187.0 IL 161 New Baden, Kell
Sandoval122.7197.5 US 50 west CarlyleWestern end of US 50 concurrency
123.0197.9 US 50 east SalemEastern end of US 50 concurrency
FayetteVandalia146.9236.4 US 40 east / IL 185 east Bluff CityEastern end of US 40/IL 185 concurrency
148.5239.0 US 40 west / IL 185 west Taylor Springs, Mulberry GroveWestern end of US 40/IL 185 concurrency
148.7239.3 I-70 Effingham, St. LouisExit 63 on I-70
No major junctions
ChristianPana178.1286.6 IL 16 west HillsboroWestern end of IL 16 concurrency
178.6287.4 IL 29 north TaylorvilleSouthern terminus of IL 29
180.2290.0 IL 16 east ShelbyvilleEastern end of IL 16 concurrency
No major junctions
US 51 Bus. north
211.2339.9 IL 48 Taylorville, Decatur
Harristown214.7345.5133 I-72 west / US 36 Springfield, DecaturSouthern end of I-72 concurrency; signed as exits 133A (east) and 133B (south)
Decatur219.2352.8138 IL 121 Decatur, Lincoln
I-72 east / US 51 Bus. south Champaign, Urbana, Decatur
Northern end of I-72 concurrency
US 51 Bus. north Clinton
239.5385.4 IL 54 Springfield, Clinton
240.0386.2 IL 10 Lincoln, Clinton
US 51 Bus. south Clinton
McLeanHeyworth251.9405.4 US 136 McLean, Rantoul
US 51 Bus. (Main Street) Bloomington
I-74 east Champaign
Southern end of I-74 concurrency
262.2422.0157A I-55 south St. Louis, SpringfieldSouthern end of I-55 concurrency
Bloomington262.4422.3157B I-55 Bus. north (Veterans Parkway)Signed as exit 134B (north) southbound
265.5427.3160 US 150 / IL 9 (Market Street) Pekin
269.1433.1163 I-74 west PeoriaNorthern end of I-74 concurrency
270.3435.0- I-55 north Chicago
I-39 begins
Northern end of I-55 concurrency; southern end of I-39 concurrency; southern terminus of I-39; I-55 exit 154
US 51 Bus. south Bloomington, Normal
Hudson275.2442.95 CR 12 (Franklin Street) Hudson
278.3447.98 IL 251 north / CR 8 (Lake Bloomington Road) KappaSouthern terminus of IL 251
WoodfordEl Paso284.9458.514 US 24 El Paso, Peoria
Woodford292.9471.422 IL 116 Peoria, Pontiac
MarshallWenona305.6491.835 IL 17 Lacon, Wenona
LaSalleLostant312.2502.441 IL 18 Henry, Streator
322.3518.751 IL 71 Hennepin, Oglesby
323.0519.852 IL 251 Peru, LaSalle
Illinois River326.5525.5Abraham Lincoln Memorial Bridge
La Salle327.3526.757 US 6 LaSalle, Peru, Ottawa
329.6530.459 I-80 LaSalle, Peru, Chicago, Des MoinesSigned as exits 59A (east) and 59B (west); I-80 exit 79
Troy Grove336.8542.066 US 52 Troy Grove
Mendota342.7551.572 US 34 Mendota, Earlville
LeePaw Paw353.1568.382Paw Paw
357.9576.087 US 30 Sterling, Rock Falls, Aurora
I-88 / IL 110 (Ronald Reagan Memorial Tollway) Moline, Rock Island, Chicago
Signed as exits 97A (east) and 97B (west); I-88 exit 78
370.1595.699 IL 38 DeKalb, Rochelle
375.1603.7104 IL 64 Sycamore, Oregon
Monroe Center381.6614.1111 IL 72 Genoa, Byron
Winnebago386.1621.4115Baxter Road
Rockford390.2628.0 US 20 west Freeport, RockfordSouthern end of US 20 concurrency
Cherry Valley392.7632.0122A US 20 east BelvidereNorthern end of US 20 concurrency
392.7632.0122BHarrison Avenue
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; exit 17 on I-90
US 20 Bus. (State Street)
Last free exit northbound
398.4641.212Riverside BoulevardToll on northbound exit and southbound entrance
Machesney Park401.9646.89 IL 173 (West Lane Road)Toll on northbound exit and southbound entrance
Rockton407.3655.5South Beloit Toll Plaza
South Beloit408.1656.83 CR 9 (Rockton Road)Last free exit southbound
414.0666.31 I-39 north / I-90 west Madison
IL 75 east
Northern end of I-39/I-90 concurrency; southern end of IL 75 concurrency
415.6668.8 IL 75 west / IL 251 south Freeport, RockfordNorthern end of IL 75 concurrency; northern terminus of IL 251
415.95669.41 US 51 north BeloitContinuation into Wisconsin
1.000 mi = 1.609 km; 1.000 km = 0.621 mi


  1. Illinois Technology Transfer Center (2007). "T2 GIS Data". Illinois Department of Transportation. Retrieved November 8, 2007.
  2. "Illinois Supplemental Freeway system proposal" (PDF). Retrieved February 17, 2015.
  3. "US 51 Environmental Impact Statement". Illinois Department of Transportation. Retrieved February 17, 2015.
  4. Google (March 19, 2017). "Overview Map of US 51" (Map). Google Maps. Google. Retrieved March 19, 2017.

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