Business routes of U.S. Route 31 in Michigan

There have been seven business routes of US Highway 31 in the state of Michigan, of which three of those routes still exist. All seven of the business routes are former sections of US Highway 31 (US 31). They connect the freeway mainline of US 31 to the various downtowns of cities bypassed by US 31. One of the current business routes, for Ludington, are business spur, connecting to US 31 on only one end, while the remaining two for Muskegon and Whitehall–Montague are business loops. The four former routes, for Niles, Holland, Hart and Pentwater, were 2 business spurs and 2 loops, respectively.