Interstate 39

Interstate 39
I-39 highlighted in red
Route information
Maintained by IDOT and WisDOT
Length:	306.14 mi (492.68 km)
Major junctions
South end:	I-55 / I-74 / US 51 in Normal, IL
	I-80 in LaSalle, IL I-88 / IL 110 (CKC) in Rochelle, IL I-90 in Rockford, IL I-43 / WIS 81 in Beloit, WI I-94 / WIS 30 in Madison, WI* I-90 / I-94 / WIS 78 in Portage, WI
North end:	US 51 / WIS 29 in Rothschild, WI
Location
States:	Illinois, Wisconsin
Counties:	IL: McLean, Woodford, Marshall, LaSalle, Lee, Ogle, Winnebago WI: Rock, Dane, Columbia, Marquette, Waushara, Portage, Marathon
Highway system
Interstate Highway System Main Auxiliary Suffixed Business Illinois State Highway System Interstate U.S. State Tollways Wisconsin State Trunk Highway System Interstate U.S. State Scenic Rustic ← IL 38 IL US 40 → ← WIS 38 WI WIS 39 →

I-90 / I-94 / WIS 78 in Portage, WI

Interstate 39 (I-39) is a highway in the midwestern United States. I-39 runs from Normal, Illinois at I-55 to Wisconsin Highway 29 (WIS 29) in Rib Mountain, Wisconsin, approximately six miles (9.7 km) southwest of Wausau. I-39 was designed to replace US Highway 51 (US 51), which in the early 1980s was one of the busiest two-lane highways in the United States. I-39 was built in the 1980s and 1990s.