M-343 (Michigan highway)

M-343 is an unsigned highway designation for a former state trunkline highway in the Upper Peninsula of Michigan. It existed in the 1930s, connecting US Highway 2 (US 2) to the Rapid River State Forest. The designation was eliminated in 1939 when the roadway was transferred back to local control. As an unsigned designation, it is not marked with signage on the road itself. The former route was located in Delta County, near Rapid River. Its precise length is difficult to determine due to the lack of historical documentation, but it was a relatively short connector route.