51 was only constructed between former IL 5 (East-West Tollway/I-88) and U.S. When proposed in 1984 as I-39, the freeway along U.S. However after reconsideration, the Route Numbering Committee approved a subsequent request by IDOT on Janufor the establishment of I-39 in a letter dated February 5, 1985. This route would provide a direct connection between Interstate Route 80 and Interstate Route 90 and would serve the Rockford Metropolitan area which as a population of over 200,000.ĪASHTO disapproved the application on December 8, 1984, instead recommending a three digit spur. Therefore, we are proposing that this 64 mile segment of freeway between FAI 90 at Cherry Valley and FAI 80 at LaSalle/Peru, be designated as Interstate Route 39 under Title 23 U.S.C. The segment south of Illinois Route 5 to Interstate Route 80, presently under construction, also meets Interstate standards. Route 51 corridor from Rockford south to Illinois Route 5 is built to Interstate standards.
The Illinois Department of Transportation (IDOT) applied for the designation of Interstate 39 to the American Association of State Highway and Transportation Officials (AASHTO) on October 22, 1984: 51 extends the freeway along side Wis 29 west to Wausau and as a solo route northward to Merrill. 51 parallels the Wisconsin River north to Mosinee, Rothschild and Wis 29, where Interstate 39 concludes. 51 from Stevens Point to a freeway completed in August 2012 leading west to Junction City and Milladore. 51 northward from Portage to Packawaukee, Plover and Stevens Point. I-39 separates with I-90/94 just beyond the Wisconsin River to again overtake U.S. I-39, I-90 and I-94 run concurrently for 29 miles along a northward heading from Madison to the outskirts of Portage. There Interstate 94 ties in from Waukesha and Milwaukee to the east to form the longest three way overlap on the Interstate system. Advancing northward, the pair pass through Janesville while en route to the capital city of Madison. I-39/90 combine there along the east side of Rockford to Beloit, Wisconsin, where they meet the south end of Interstate 43. 20 turns I-39 east to Interstate 90, the Jane Addams Memorial (Northwest) Tollway. North from there, the freeway continues to I-88 outside Rochelle and U.S.
51 to Peru and La Salle, where it meets Interstate 80. A mostly rural route, I-39 begins on the north side of Normal at I-55, overtaking U.S. Interstate 39 runs northward through Illinois and Wisconsin as a long distance bypass for traffic around the Chicago and Milwaukee metropolitan areas.