There are 11 US Post Offices in Washington County serving a total of 110,049 residents equating to 10,004 residents per post office. It's estimated that approximately 175,650 packages are handled across the 11 county post offices annually. Washington County is a county in the U.S. state of Wisconsin. As of the 2010 census, the population was 131,887. Its county seat is West Bend. The county was created from Wisconsin Territory in 1836 and organized in 1845. It was named after President George Washington. Washington County is part of in the Milwaukee-Waukesha-West Allis, WI Metropolitan Statistical Area."