Eagle River is an unincorporated community and census-designated place in the U.S. state of Michigan. It is the county seat of Keweenaw County. Its population was 65 at the 2020 census, which makes it by far the least-populated county seat in the state of Michigan. As an unincorporated community, Eagle River has no legal autonomy and is part of Allouez Township and Houghton Township.