The Kalamazoo River is a river in the U.S. state of Michigan. The river is 130 miles (210 km) long from the junction of its North and South branches to its mouth at Lake Michigan, with a total length extending to 178 miles (286 km) when one includes the South Branch. The river's watershed drains an area of approximately 2,020 square miles (5,200 km²) and drains portions of eight counties in southwest Michigan: Allegan, Barry, Eaton, Van Buren, Kalamazoo, Calhoun, Jackson, Hillsdale, Kent and Ottawa.