There are 17 US Post Offices in Washington County serving a total of 206,529 residents equating to 12,149 residents per post office. It's estimated that approximately 329,643 packages are handled across the 17 county post offices annually. Washington County is a county located in the northwest part of the U.S. state of Arkansas. As of the 2010 census, the population was 203,065, making it the third-most populous county in Arkansas. The county seat is Fayetteville. Washington County is Arkansas's 17th county, formed on October 17, 1828, and named for George Washington, the first President of the United States. Washington County is part of the Fayetteville-Springdale-Rogers, AR-MO Metropolitan Statistical Area."