Illinois Route 251

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Illinois Route 251 marker

Illinois Route 251
Route information
Maintained by IDOT
Length: 135.32 mi[2] (217.78 km)
Existed: Early 1970s[1] – present
Major junctions
South end: I-39 / US 51 in Hudson
  US 24 in El Paso
I-39 / US 51 in LaSalle
US 6 in Peru
I-80 in Peru
US 52 in Troy Grove
US 34 in Mendota
US 52 in Mendota
US 30 in Compton
I-88 / IL 110 in Rochelle
US 20 in Rockford
North end: US 51 / IL 75 in South Beloit
Highway system
IL 250 I-255

Illinois Route 251 is a north–south state road that runs on the former alignment of U.S. Route 51 before Interstate 39 was built in central Illinois. It runs from U.S. 51 at the border with Wisconsin to I-39 and U.S. 51 south of Kappa. Illinois 251 is 135.32 miles (217.78 km) long.[2]

Route description[edit]

Illinois 251 runs parallel to Interstate 39 and U.S. 51 for most of the length of I-39 in Illinois. Like Illinois Route 351, it can be considered a spur, loop or alternate of its parent route, U.S. 51. Illinois 251 terminates about 8 mi (13 km) north of the southern terminus of I-39.

The road parallels the east bank of the Rock River through Rockford, where the highway goes north on Eleventh Street, west on Harrison, north on Kishwaukee, west on Walnut then split between northbound Third and southbound Second through downtown Rockford. After donwtown, both directions take the southbound lanes' Second Street name as a divided urban expressway (also badged as Martin Luther King Jr. Memorial Drive) for a couple of miles north of downtown Rockford. It stays Second Street through Loves Park, Machesney Park and Roscoe until its north endpoint at US 51 and Illinois 75 in South Beloit


Illinois 251 was established in 1982 when first segment of I-39 opened between Rockford and Bloomington. In 1992, the final segment of I-39 opened north of Bloomington. The remaining stretch of Former U.S. 51 became Illinois 251.[3] The initial designation of I-39 was U.S. Route 51 until 1992.

External links[edit]


  1. ^ Carlson, Rich. Illinois Highways Page: Routes 200 thru end. Last updated April 15, 2005. Retrieved May 12, 2006.
  2. ^ a b Illinois Technology Transfer Center (2006). "T2 GIS Data". Retrieved 2007-11-08. 
  3. ^ AARoads. Interstate 39 @