Keweenaw County is a county in the western Upper Peninsula of the U.S. state of Michigan. As of the 2020 census, the county's population was 2,046, making it Michigan's least populous county. It is also the state's largest county by total area, including the waters of Lake Superior, as well as the state's northernmost county. The county seat is Eagle River. Located at the northeastern end of the Keweenaw Peninsula, Keweenaw County is part of the Houghton, Michigan micropolitan area.