M-24 is a state trunkline highway in the U.S. state of Michigan that extends through Southeast Michigan and The Thumb, from northeast Auburn Hills to Unionville. It starts at an interchange with Interstate 75 (I-75) and ends where it merges with M-25. While the M-24 designation is similar to that of US Highway 24 (US 24) which has a northern terminus located only a few miles from the southern terminus of M-24, M-24 was never part of US 24.