| State: | MI |
| Type: | M |
| Route: | 157 |
| Alternate Name: | Roscommon Road |
| Map Custom: | yes |
| Map Notes: | M-157 highlighted in red |
| Length Mi: | 1.193 |
| Length Round: | 3 |
| Established: | 1932 |
| Direction A: | South |
| Terminus A: | near Prudenville |
| Direction B: | North |
| Terminus B: | near Prudenville |
| Counties: | Roscommon |
| Previous Type: | M |
| Previous Route: | 156 |
| Next Type: | M 1926 |
| Next Route: | 158 |
M-157 is a short state trunkline highway in the US state of Michigan. The highway is entirely within Roscommon County in the Lower Peninsula. It is the fourth-shortest state highway in the system, and it serves as a connector route between M-18 and M-55 just east of Prudenville. The current roadway was built and designated as M-157 in the 1930s.
M-157 begins at an intersection with M-55 east of Prudenville and Houghton Lake. The trunkline angles to the northwest before turning north near Ryan Lake. Serving as a short connector, the highway travels north through the Roscommon State Forest terminating just over a mile later at a junction with M-18.[1] A newspaper article in 1972 describing the shortest highways in the state to "important places" listed M-157 as a "short-cut" between the two highways.[2] The Michigan Department of Transportation (MDOT) conducts surveys in 2008 that showed 496 vehicles per day, on average.[3]
M-157 was originally designated in 1931 as a connector route between M-55 and US 27 (present-day M-18).[4] [5] Just a year later, that version was decommissioned, and the road obliterated. A new alignment, the present-day routing of M-157, was then commissioned just to the east.[6] [7]