U.S. Route 31 in Michigan

US Highway 31
US 31 highlighted in red
Route information
Maintained by MDOT
Length:	356.527 mi (573.775 km)
Existed:	November 11, 1926 (1926-11-11) – present
Tourist routes:	Lake Michigan Circle Tour West Michigan Pike Pure Michigan Byway
Major junctions
South end:	US 31 near Niles
	US 12 near Niles I-94 / I-196 near Benton Harbor I-196 at Holland I-96 near Muskegon US 10 at Ludington US 131 at Petoskey
North end:	I-75 near Mackinaw City
Location
Counties:	Berrien, Van Buren, Allegan, Ottawa, Muskegon, Oceana, Mason, Manistee, Benzie, Grand Traverse, Antrim, Charlevoix, Emmet, Cheboygan
Highway system
United States Numbered Highway System List Special Divided Replaced Michigan State Trunkline Highway System Interstate US State Byways ← M-30 M-31 →

US Highway 31 (US 31) is a part of the United States Numbered Highway System that runs from Alabama to the Lower Peninsula of the US state of Michigan. In Michigan, it is a state trunkline highway that runs from the Indiana–Michigan state line at Bertrand Township north to its terminus at Interstate 75 (I-75) south of Mackinaw City. Along its 356.5-mile-long (573.7 km) route, US 31 follows the Michigan section of the St. Joseph Valley Parkway as well as other freeways and divided highways northward to Ludington. North of there, the trunkline is a rural undivided highway through the Northern Michigan tourist destinations of Traverse City and Petoskey before terminating south of Mackinaw City. Along its route, US 31 has been dedicated in memory of a few different organizations, and sections of it carry the Lake Michigan Circle Tour (LMCT) moniker. Four bridges used by the highway have been recognized for their historic character as well.

The first highways along the route of the modern US 31 corridor were the West Michigan Pike, an auto trail from 1913, and later a pair of state trunklines (the original M-11 and M-58) in 1919. These state highways were redesignated US 31 on November 11, 1926, when the US Highway System was approved. Since then, the highway has been realigned in places. The highway crossed the Straits of Mackinac by ferry for about a decade in the 1920s and 1930s before the Mackinac Bridge was built, connecting to US 2 north of St. Ignace. Later, sections were converted into freeways starting in the 1950s. These segments opened through the subsequent decades with the last one opening in 2003. Future plans by the Michigan Department of Transportation (MDOT) are to finish the St. Joseph Valley Parkway and bypass Grand Haven.