There are 2 US Post Offices in Broadwater County serving a total of 4,473 residents equating to 2,237 residents per post office. It's estimated that approximately 7,139 packages are handled across the 2 county post offices annually. Broadwater County is a county located in the U.S. state of Montana. As of the 2010 census, the population was 5,612. Its county seat is Townsend. The county was named for Charles Arthur Broadwater, a noted Montana railroad, real estate, and banking magnate."