| State: | MI |
| Type: | M 1948 |
| Route: | 146 |
| Map Custom: | yes |
| Map Notes: | M-146 highlighted in red on a modern map |
| Formed: | 1933 |
| Deleted: | 1966 |
| Length Mi: | 0.910 |
| Length Ref: | [1] |
| Direction A: | South |
| Terminus A: | in Port Huron |
| Direction B: | North |
| Terminus B: | in Port Huron Township |
| Counties: | St. Clair |
| Previous Type: | M 1948 |
| Previous Route: | 144 |
| Previous Dab: | 1940–1973 |
| Next Type: | M 1973 |
| Next Route: | 147 |
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.
As the highway last existed, its southern end was at an intersection with M-21 (Lapeer Road) in a residential area of Port Huron west of the Black River. Following what is today named the Lapeer Connector, M-146 ran northward for about 0.9miles to an interchange with I-94/US 25 where it terminated.
When the route debuted in 1933 it served as a connector between US 25 in southwest Port Huron and M-21 along the west side of town.[2] [3] In 1954 a new approach was built from M-21 to the foot of the Blue Water Bridge, and M-146 was extended northward and easterly, designated along this new route.[4] [5] By 1958, this newer segment was converted to freeway specifications,[6] [7] and in 1964, with the completion of the I-94/US 25 freeway, M-146 was removed from that portion of the route.[8] [9] By the next year, the M-146 designation only remained along the stretch of freeway which now serves as the exit 274 interchange on I-94, and was removed from 24th Street through town.[10] [9] The alignment of the freeway stretch of M-146 was shifted slightly as well, allowing for a smoother transition between it and westbound I-94. In addition, the diamond interchange with Water Street along the Blue Water Bridge approach was reconstructed and appropriated into the alignment of I-94.[11] In 1966, with the completion of a new freeway alignment for M-21 between Wadhams and downtown Port Huron, the M-146 designation was removed from the state trunkline system,[10] [12] and has not been used since. The connector between Lapeer Street and present-day I-94 is now known as the Lapeer Connector[13] and Connector 69.[14]