Clare County is a county in the U.S. state of Michigan. As of the 2020 Census, the population was 30,856. The county seat is Harrison. The county was created by the Michigan Legislature from part of Michilimackinac County in 1840, named Kaykakee County after a Sauk Indian Chief. It was renamed Clare County in 1843 after County Clar…Clare County is a county in the U.S. state of Michigan. As of the 2020 Census, the population was 30,856. The county seat is Harrison. The county was created by the Michigan Legislature from part of Michilimackinac County in 1840, named Kaykakee County after a Sauk Indian Chief. It was renamed Clare County in 1843 after County Clare in Ireland. The county was administered by a succession of other Michigan counties prior to the organization of county government in 1871. Farwell was the first county seat; in 1877 the county seat was moved to Harrison.