Interstate 94 (I-94) is a part of the Interstate Highway System that runs from Billings, Montana, to the Lower Peninsula of the US state of Michigan. In Michigan, it is a state trunkline highway that enters the state south of New Buffalo and runs eastward through several metropolitan areas in the southern section of the state. The highway serves Benton Harbor–St. Joseph near Lake Michigan before turning inland toward Kalamazoo and Battle Creek on the west side of the peninsula. Heading farther east, I-94 passes through rural areas in the middle of the southern Lower Peninsula, crossing I-69 in the process. I-94 then runs through Jackson, Ann Arbor, and portions of Metro Detroit, connecting Michigan's largest city to its main airport. Past the east side of Detroit, the Interstate angles northeasterly through farmlands in The Thumb to Port Huron, where the designation terminates on the Blue Water Bridge at the Canadian border. The first segment of what later became I-94 within the state, the Willow Run Expressway, was built near Ypsilanti and Belleville in 1941, with an easterly extension to Detroit in 1945. This expressway was initially numbered M-112. In the mid-1950s, state and federal officials planned an Interstate to replace the original route of US Highway 12 (US 12). By 1960, the length of I-94 was completed from Detroit to New Buffalo. Two years later, the US 12 designation was dropped from the freeway. Subsequent extensions in the 1960s completed most of the rest of the route, including the remaining sections between Detroit and Port Huron which superseded the routing of US 25. The last segment opened to the public in 1972 when Indiana completed its connection across the state line. Since completion, I-94 has remained relatively unchanged; a few interchanges have been rebuilt, a second span was constructed for the Blue Water Bridge, and, in 1987, a plane crashed on the freeway during takeoff from the airport in Detroit. The routing of I-94 is notable for containing the first full freeway-to-freeway interchange in the United States, connecting to the Lodge Freeway (M-10), and for comprising the first complete border-to-border toll-free freeway in a state in the United States. The highway has one auxiliary route, I-194, which serves downtown Battle Creek, and eight business routes. Various segments have been dedicated to multiple people and places. Route description The entire length of I-94 is listed on the National Highway System,