what is m-30 (michigan highway)?
It is a state trunkline highway in the U.S. state of Michigan.
M-30 (Michigan highway)
M-30 is a state trunkline highway in the U.S. state of Michigan that runs in a north–south direction from the Midland area to West Branch. 
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M-30 (Michigan highway) [SEP] Introduction
M-30 is a state trunkline highway in the U.S. state of Michigan that runs in a north–south direction from the Midland area to West Branch. The highway runs through rural parts of three counties in the Lower Peninsula. The southern end runs along the Michigan Meridian and parallel to the Tittabawassee River. Prior to 1962, M-30's southern terminus was at a junction with M-46 in Merrill. Since then, the segment south of US Highway 10 (US 10) was returned to local control and decommissioned. In May 2009, M-30 was extended southerly from US 10 to M-20, restoring some of the highway decommissioned in the 1960s to M-30.