Interstate 43 (I-43) is a 191.55-mile-long (308.27 km) Interstate Highway located entirely within the US state of Wisconsin, connecting I-39/I-90 in Beloit with Milwaukee and I-41, U.S. Highway 41 (US 41) and US 141 in Green Bay. State Trunk Highway 32 (WIS 32) runs concurrently with I-43 in two sections and I-94, I-894, US 10, US 41, US 45, and WIS 57 overlap I-43 once each. There are no auxiliary or business routes connected to I-43, though an alternate route to direct traffic during road closures is signed along local and state highways from Milwaukee County north into Brown County.

Interstate 39 (I-39) is a highway in the Midwestern United States. I-39 runs from Normal, Illinois, at I-55 to State Trunk Highway 29 (WIS 29) in the town of Rib Mountain, Wisconsin, which is approximately six miles (9.7 km) south of Wausau. I-39 was designed to replace U.S. Route 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.