Black River is a 78.8 mi river in the U.S. state of Michigan, flowing mostly northward through four Northern Michigan counties: Otsego, Montmorency, Presque Isle, and Cheboygan. The Black River flows into the Cheboygan River at 45.60361°N, -84.46306°W, just south of the city of Cheboygan, and then into Lake Huron. The main branch of the Black River originates in Charlton Township in east-central Otsego County near the boundary with Montmorency County. The East Branch of the Black River rises less than a mile to the east in Vienna Township in Montmorency County. The other major tributaries, Canada Creek, Tomahawk Creek and the Rainy River all rise in northern Montmorency County. Tributaries (from the mouth):