M-38 is an east–west state trunkline highway in the Upper Peninsula (UP) of the U.S. state of Michigan. Its west end starts in Ontonagon and runs east to Baraga, some 42.225 miles (67.955 km) apart. The highway crosses streams and rivers in forest lands and provides access to a casino. The east end is located by the Keweenaw Bay of Lake Superior in the Keweenaw Bay Indian Community.

Ontonagon is a village in the Upper Peninsula of the U.S. state of Michigan. The population was 1,285 at the 2020 census. It is the county seat of Ontonagon County, and is the only incorporated place within the county.