# 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).

## Route description

US 51 enters Illinois from Kentucky at Cairo, Illinois. The highway heads northbound to Mounds, near Cairo, 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 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 join I-90, 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 (IL 75) west to the intersection of IL 251, and then turns north through South Beloit, Illinois 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 between Rockford and Bloomington–Normal 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 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.

## Major intersections

| County | Location | mi | km | Exit | Destinations | Notes |
| Alexander | Cairo | 0.0 | 0.0 | | US 51 south / US 60 east / US 62 east – Wickliffe | Continuation into Kentucky |
| Alexander | Cairo | 0.2 | 0.32 | | US 60 west / US 62 west to I-57 south – Charleston | Northern end of US 60/US 62 concurrency |
| Alexander | Cairo | 4.5 | 7.2 | | IL 37 north – Mound City IL 3 north | Southern end of IL 3 concurrency; southern termini of IL 3 and IL 37 |
| Alexander | Cairo | 5.3 | 8.5 | 1 | I-57 south / IL 3 north – Olive Branch, Sikeston, MO | Northern end of IL 3 concurrency; southern end of I-57 concurrency |
| Pulaski | ​ | 11.4 | 18.3 | 8 | Mounds Road | |
| Pulaski | ​ | 21.4 | 34.4 | 18 | Ullin Road | |
| Union | Dongola | 28.2 | 45.4 | 24 | Dongola Road | |
| Union | Dongola | 28.8 | 46.3 | 25 | I-57 north – Chicago | Northern end of I-57 concurrency; Northbound exit and southbound entrance |
| Union | Anna | 36.0 | 57.9 | | IL 146 – Jonesboro, Vienna | |
| Jackson | Carbondale | 55.0 | 88.5 | | IL 13 – Murphysboro, Marion | |
| Jackson | De Soto | 61.3 | 98.7 | | IL 149 – Murphysboro, Hurst | |
| Perry | Du Quoin | 72.4 | 116.5 | | IL 14 east – Christopher | Western terminus of IL 14 |
| Perry | Du Quoin | 75.5 | 121.5 | | IL 152 west – Pyatts | Eastern terminus of IL 152 |
| Perry | Sunfield | 80.4 | 129.4 | | IL 154 – Red Bud, Sesser | |
| Washington | Ashley | 98.0 | 157.7 | | IL 15 west – East St. Louis | Western end of IL 15 concurrency |
| Washington | Ashley | 100.9 | 162.4 | | IL 15 east – Mount Vernon | Eastern end of IL 15 concurrency |
| Washington | Richview | 105.7 | 170.1 | | I-64 – Mount Vernon, East St. Louis | I-64 exit 61 |
| Washington | Irvington | 109.6 | 176.4 | | IL 177 west – Belleville | Western terminus of IL 177 |
| Jefferson | No major junctions | No major junctions | No major junctions | No major junctions | No major junctions | No major junctions |
| Marion | Centralia | 116.2 | 187.0 | | IL 161 – New Baden, Kell | |
| Marion | Sandoval | 122.7 | 197.5 | | US 50 west – Carlyle | Western end of US 50 concurrency |
| Marion | Sandoval | 123.0 | 197.9 | | US 50 east – Salem | Eastern end of US 50 concurrency |
| Fayette | Vandalia | 146.9 | 236.4 | | US 40 east / IL 185 east – Bluff City | Eastern end of US 40/IL 185 concurrency |
| Fayette | Vandalia | 148.5 | 239.0 | | US 40 west / IL 185 west – Taylor Springs, Mulberry Grove | Western end of US 40/IL 185 concurrency |
| Fayette | Vandalia | 148.7 | 239.3 | | I-70 – Effingham, St. Louis | Exit 63 on I-70 |
| Shelby | No major junctions | No major junctions | No major junctions | No major junctions | No major junctions | No major junctions |
| Christian | Pana | 178.1 | 286.6 | | IL 16 west – Hillsboro | Western end of IL 16 concurrency |
| Christian | Pana | 178.6 | 287.4 | | IL 29 north – Taylorville | Southern terminus of IL 29 |
| Christian | ​ | 180.2 | 290.0 | | IL 16 east – Shelbyville | Eastern end of IL 16 concurrency |
| Shelby | No major junctions | No major junctions | No major junctions | No major junctions | No major junctions | No major junctions |
| Macon | ​ | 207.3 | 333.6 | | Elwin, Mt Zion | Northbound exit, southbound entrance |
| Macon | ​ | 210 | 340 | | Decatur, Elwin, Mt Zion | Interchange |
| Macon | ​ | 211.2 | 339.9 | | IL 48 – Taylorville, Decatur | |
| Macon | Harristown | 214.7 | 345.5 | 133 | I-72 west / US 36 – Springfield, Decatur | Southern end of I-72 concurrency; signed as exits 133A (east) and 133B (south) |
| Macon | Decatur | 219.2 | 352.8 | 138 | IL 121 – Decatur, Lincoln | |
| Macon | Decatur | 222.2 | 357.6 | 141 | I-72 east – Champaign, Urbana, Decatur | Northern end of I-72 concurrency |
| DeWitt | Clinton | 237.9 | 382.9 | | US 51 Bus. north – Clinton | |
| DeWitt | Clinton | 239.5 | 385.4 | | IL 54 – Springfield, Clinton | |
| DeWitt | Clinton | 240.0 | 386.2 | | IL 10 – Lincoln, Clinton | |
| DeWitt | Clinton | 242.0 | 389.5 | | US 51 Bus. south – Clinton | |
| McLean | Heyworth | 251.9 | 405.4 | | US 136 – McLean, Rantoul | |
| McLean | ​ | 260.5 | 419.2 | 135 | US 51 Bus. (Main Street) – Bloomington I-74 east – Champaign | Southern end of I-74 concurrency |
| McLean | ​ | 262.2 | 422.0 | 157A | I-55 south – St. Louis, Springfield | Southern end of I-55 concurrency |
| McLean | Bloomington | 262.4 | 422.3 | 157B | I-55 BL north (Veterans Parkway) | Signed as exit 134B (north) southbound |
| McLean | Bloomington | 265.5 | 427.3 | 160 | US 150 / IL 9 (Market Street) – Pekin | |
| McLean | ​ | 269.1 | 433.1 | 163 | I-74 west – Peoria | Northern end of I-74 concurrency |
| McLean | ​ | 270.3 | 435.0 | — | I-55 north – Chicago I-39 north | Northern end of I-55 concurrency; southern end of I-39 concurrency; southern terminus of I-39; I-55 exit 154 |
| McLean | ​ | 272.1 | 437.9 | 2 | US 51 Bus. south – Bloomington, Normal | |
| McLean | Hudson | 275.2 | 442.9 | 5 | CR 12 (Franklin Street) – Hudson | |
| McLean | ​ | 278.3 | 447.9 | 8 | IL 251 north / CR 8 (Lake Bloomington Road) – Kappa | Southern terminus of IL 251 |
| Woodford | El Paso | 284.9 | 458.5 | 14 | US 24 – El Paso, Peoria | |
| Woodford | Woodford | 292.9 | 471.4 | 22 | IL 116 – Peoria, Pontiac | |
| Woodford | Minonk | 297.5 | 478.8 | 27 | Minonk | |
| Marshall | Wenona | 305.6 | 491.8 | 35 | IL 17 – Lacon, Wenona | |
| LaSalle | Lostant | 312.2 | 502.4 | 41 | IL 18 – Henry, Streator | |
| LaSalle | Tonica | 319.2 | 513.7 | 48 | Tonica | |
| LaSalle | ​ | 322.3 | 518.7 | 51 | IL 71 – Hennepin, Oglesby | |
| LaSalle | ​ | 323.0 | 519.8 | 52 | IL 251 – Peru, LaSalle | |
| LaSalle | Oglesby | 324.4 | 522.1 | 54 | Oglesby | |
| LaSalle | Illinois River | 326.5 | 525.5 | Abraham Lincoln Memorial Bridge | Abraham Lincoln Memorial Bridge | Abraham Lincoln Memorial Bridge |
| LaSalle | La Salle | 327.3 | 526.7 | 57 | US 6 – LaSalle, Peru, Ottawa | |
| LaSalle | ​ | 329.6 | 530.4 | 59 | I-80 – LaSalle, Peru, Chicago, Des Moines | Signed as exits 59A (east) and 59B (west); I-80 exit 79 |
| LaSalle | Troy Grove | 336.8 | 542.0 | 66 | US 52 – Troy Grove | |
| LaSalle | Mendota | 342.7 | 551.5 | 72 | US 34 – Mendota, Earlville | |
| Lee | Paw Paw | 353.1 | 568.3 | 82 | Paw Paw | |
| Lee | ​ | 357.9 | 576.0 | 87 | US 30 – Sterling, Rock Falls, Aurora | |
| Lee | Steward | 363.9 | 585.6 | 93 | Steward | |
| Ogle | Rochelle | 368.0 | 592.2 | 97 | I-88 Toll / IL 110 (CKC) (Ronald Reagan Memorial Tollway) – Moline, Rock Island, Chicago | Signed as exits 97A (east) and 97B (west); I-88 exit 78 |
| Ogle | Rochelle | 370.1 | 595.6 | 99 | IL 38 / Lincoln Highway – DeKalb, Rochelle | |
| Ogle | Lindenwood | 375.1 | 603.7 | 104 | IL 64 – Sycamore, Oregon | |
| Ogle | Monroe Center | 381.6 | 614.1 | 111 | IL 72 – Genoa, Byron | |
| Winnebago | ​ | 386.1 | 621.4 | 115 | Baxter Road | |
| Winnebago | Rockford | 390.2 | 628.0 | | US 20 west (Rockford Bypass) – Freeport, Rockford | Southern end of US 20 concurrency |
| Winnebago | Cherry Valley | 392.7 | 632.0 | 122A | US 20 east – Belvidere | Northern end of US 20 concurrency |
| Winnebago | Cherry Valley | 392.7 | 632.0 | 122B | Harrison Avenue | |
| Winnebago | Cherry Valley | 393.4 | 633.1 | | I-90 Toll 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 |
| Winnebago | Rockford | 395.1 | 635.9 | 15 | US 20 Bus. (State Street) | Last free exit northbound |
| Winnebago | Rockford | 398.4 | 641.2 | 12 | Riverside Boulevard | Toll on northbound exit and southbound entrance |
| Winnebago | Machesney Park | 401.9 | 646.8 | 9 | IL 173 (West Lane Road) – Machesney Park | Toll on northbound exit and southbound entrance |
| Winnebago | Rockton | 407.3 | 655.5 | South Beloit Toll Plaza | South Beloit Toll Plaza | South Beloit Toll Plaza |
| Winnebago | South Beloit | 408.1 | 656.8 | 3 | CR 9 (Rockton Road) | Last free exit southbound |
| Winnebago | South Beloit | 414.0 | 666.3 | 1 | I-39 north / I-90 west – Madison IL 75 east (Manchester Road) | Northern end of I-39/I-90 concurrency; southern end of IL 75 concurrency |
| Winnebago | South Beloit | 415.6 | 668.8 | | IL 75 west (Gardner Street) / IL 251 south (North 2nd Street) – Freeport, Rockford | Northern end of IL 75 concurrency; northern terminus of IL 251 |
| Winnebago | South Beloit | 415.95 | 669.41 | | US 51 north (Dearborn Street) – Beloit | Continuation into Wisconsin |
| 1.000 mi = 1.609 km; 1.000 km = 0.621 mi Concurrency terminus Incomplete access Tolled |||||||