U.S. Route 31 (US 31) is a north‑south United States Numbered Highway that traverses the western side of Michigan’s Lower Peninsula. Within the state, the highway extends from the Indiana state line at New Buffalo north to its terminus at US 2 near Mackinaw City, covering approximately 272 mi (438 km). The route serves a mix of coastal towns, agricultural areas, and the Grand Rapids metropolitan region, and portions of it have been upgraded to freeway standards.
Route description
Southern segment (New Buffalo – Southwest Michigan)
US 31 enters Michigan at the state line on the north side of the Blue Water Bridge, crossing the St. Joseph River into New Buffalo. It proceeds northward as a surface road, intersecting I‑94 at exit 9 and providing access to the town of New Buffalo and the nearby Lake Michigan shoreline. The highway continues through the communities of St. Joseph, Benton Harbor, and South Benton Harbor, where it briefly joins I‑196/US 31 Business.
Central segment (Coastal corridor – Grand Rapids area)
North of the Twin Cities, US 31 follows the Lake Michigan coast through Holland, where it meets US 31 Business and the Holland Tunnel Park. At the Holland–Grand Rapids corridor, US 31 merges onto I‑196, forming a concurrent freeway stretch that runs eastward toward Grand Rapids. The combined I‑196/US 31 freeway bypasses the city’s core, providing interchanges with I‑96 (exit 44) and US 131. US 31 departs I‑196 at exit 44, continuing north as a limited‑access highway that skirts the western edge of Grand Rapids and connects with I‑96 via a cloverleaf interchange.
Northern segment (From Grand Rapids to Mackinaw City)
Leaving the metropolitan area, US 31 proceeds north as a freeway through the Lake Michigan shoreline towns of White Lake, White Cloud, and Muskegon. In Muskegon, US 31 separates from I‑96 and becomes a divided surface highway that traverses the city’s downtown and crosses the Muskegon River via the Veterans Memorial Bridge. The highway continues northward through Manistee, Traverse City, and Petoskey, largely as a two‑lane rural road with occasional passing lanes. The northern terminus is at an intersection with US 2 just south of the Mackinac Bridge in Mackinaw City.
History
Establishment
US 31 was designated as part of the original 1926 United States Numbered Highway System. The Michigan portion originally followed a series of pre‑existing state trunkline routes that had been assigned numbers M‑13, M‑45, and M‑61.
Extensions and realignments
In 1934, US 31 was extended northward from its original terminus at US 31’s junction with US 131 to reach US 2 near Mackinaw City, providing a continuous north‑south corridor along the western lakefront. Throughout the 1950s and 1960s, segments between Holland and Grand Rapids were upgraded to a four‑lane divided highway, and a freeway bypass of St. Joseph and Benton Harbor was completed in 1969. The freeway portion between Grand Rapids and Muskegon was constructed in phases from 1970 to 1982, creating the current I‑196/US 31 concurrency.
Recent developments
Since the early 2000s, the Michigan Department of Transportation (MDOT) has pursued additional upgrades to convert remaining two‑lane sections into limited‑access freeways. The most notable project is the US 31 Freeway extension between US 31 Business in South Benton Harbor and the I‑196 interchange, completed in 2015.
Major intersections
| Milepost (mi) | Location | Intersecting route(s) | Notes |
|---|---|---|---|
| 0.0 | New Buffalo (state line) | — | Entry from Indiana |
| 4.2 | New Buffalo | I‑94 (exit 9) | Connection to interstate east‑west corridor |
| 22.5 | St. Joseph | US 31 Business | Business loop through downtown |
| 30.7 | Benton Harbor | I‑196/US 31 Business | Begins freeway concurrency |
| 45.8 | Holland | US 31 Business | Access to downtown Holland |
| 64.6 | Grand Rapids (west) | I‑96 (exit 44) | Major interstate interchange |
| 85.3 | White Lake | US 31 Business | Spur into the town |
| 107.9 | Muskegon | US 10/US 31 Business | Crossing of Muskegon River |
| 135.2 | Manistee | M‑55 | Connection to interior routes |
| 166.4 | Petoskey | US 131 | Major north‑south junction |
| 272.0 | Mackinaw City | US 2 | Northern terminus |
Future plans
MDOT’s long‑range transportation plan includes converting the remaining two‑lane rural stretch between White Lake and Manistee to a four‑lane divided highway, subject to funding and environmental review. Additional safety improvements—such as widening shoulders, installing median barriers, and upgrading intersections—are scheduled for the 2020s.
Cultural and economic significance
US 31 serves as a principal corridor for tourism along Michigan’s “Lake Michigan circle tour,” providing access to beaches, state parks, and historic lighthouses. In the Grand Rapids area, the highway functions as a commuter route and supports regional freight movement, linking several industrial parks with the interstate system.
References
- Michigan Department of Transportation, Michigan Highway Log (latest edition).
- Federal Highway Administration, U.S. Numbered Highway System – Route Log (2023).
- Historic American Engineering Record, “U.S. Highway 31, Michigan” (archival documentation).
