Interstate 75 in Michigan

Interstate 75
I-75 highlighted in red
Route information
Maintained by MDOT and MBA
Length	395.916 mi[1] (637.165 km)
Existed	1959[2]–present
History	Completed November 1, 1973[3]
Tourist routes	Lake Erie Circle Tour Lake Michigan Circle Tour Lake Huron Circle Tour Lake Superior Circle Tour
NHS	Entire route
Major junctions
South end	I-75 near Erie at the Ohio state line
Major intersections	I-96 in Detroit I-94 in Detroit I-696 near Royal Oak US 23 near Grand Blanc I-69 in Flint US 10 near Bay City US 127 near Grayling US 31 near Mackinaw City US 2 in St. Ignace M-28 near Sault Ste. Marie
North end	International Bridge in Sault Ste. Marie
Location
Country	United States
State	Michigan
Counties	Monroe, Wayne, Oakland, Genesee, Saginaw, Bay, Arenac, Ogemaw, Roscommon, Crawford, Otsego, Cheboygan, Emmet, Mackinac, Chippewa
Highway system
Interstate Highway System Main Auxiliary Suffixed Business Future Michigan State Trunkline Highway System Interstate US State Byways
← M-74 → BL I-75

Interstate 75 (I-75) is a part of the Interstate Highway System that runs north–south from Miami, Florida, to Sault Ste. Marie in the Upper Peninsula of the US state of Michigan. I-75 enters the state from Ohio in the south, north of Toledo, and runs generally northward through Detroit, Pontiac and Bay City, crosses the Mackinac Bridge, and ends at the Canadian border in Sault Ste. Marie. The freeway runs for approximately 396 miles (637 km) on both of Michigan's major peninsulas. The landscapes traversed by I-75 include Southern Michigan farmland, northern forests, suburban bedroom communities, and the urban core of Detroit. The freeway also uses three of the state's monumental bridges to cross major bodies of water. There are four auxiliary Interstates in the state related to I-75, as well as nine current or former business routes, with either Business Loop I-75 (BL I-75) or Business Spur I-75 (BS I-75) designations.

The freeway bears several names in addition to the I-75 designation. The southern segment was called the Detroit–Toledo Expressway during planning in the 1950s and 1960s. Through Detroit, I-75 is the Fisher Freeway or the Walter P. Chrysler Freeway, named for pioneers in the auto industry. Sections on either side of the Mackinac Bridge are the G. Mennen Williams Freeway or the Prentiss M. Brown Freeway, named for politicians who helped get the bridge built. Officially, the entire length is the American Legion Memorial Highway, after the organization of the same name. Various sections carry components of the four Great Lakes Circle Tours in the state.

Several Indian trails spanned the state along the general path of the contemporary freeway. After statehood, several of these were converted into plank roads that later became some of the first state highways. In the 1920s, five of these were added to the United States Numbered Highway System: US Highway 2 (US 2), US 10, US 24, US 25, and US 27. In the 1950s, a Michigan Turnpike was proposed as a tolled, controlled-access highway in the Lower Peninsula. After passage of the Federal Highway Act of 1956, this turnpike proposal was shelved as a free Interstate Highway was planned. Construction started in 1957, signs went up in 1959, and I-75 was completed in 1973. Since completion, the freeway has been upgraded with the construction of the Zilwaukee Bridge near Saginaw and improved connections to the Ambassador Bridge in Detroit.