Branch County is a county in the U.S. state of Michigan. As of the 2020 Census, the population was 44,862. The county seat is Coldwater. One of the "cabinet counties", it was named for John Branch, U.S. Secretary of the Navy under President Andrew Jackson. The county was founded in 1829, and was organized in 1833. Branch County comprises the Coldwater, MI Micropolitan Statistical Area.