Keweenaw County is a county located in the Upper Peninsula of the U.S. state of Michigan. As of the 2010 census, the population was 2,156, making it the least populous county in Michigan. The county seat is Eagle River. The county was set off and organized in 1861. It is believed that Keweenaw is "a Native American word meaning 'portage or place where portage is made.'" (See List of Michigan county name etymologies.)