M-146 was a state trunkline highway in the US state of Michigan that initially served as a bypass for traffic going around Port Huron and as a short cut for traffic between U.S. Highway 25 (US 25) and M-21. Later it connected to the Blue Water Bridge before it was truncated to its final form. Segments of M-146 still exist today as state highways as part of Interstate 94 (I-94) and I-69 and the Lapeer Connector.