There are 17 US Post Offices in Washoe County serving a total of 292,669 residents equating to 17,216 residents per post office. It's estimated that approximately 467,132 packages are handled across the 17 county post offices annually. Washoe County is a county located in the U.S. state of Nevada. As of the 2010 census, the population was 421,407, making it the second-most populous county in Nevada. Its county seat is Reno. Washoe County is included in the Reno, NV Metropolitan Statistical Area."