There are 7 US Post Offices in Wasco County serving a total of 24,359 residents equating to 3,480 residents per post office. It's estimated that approximately 38,880 packages are handled across the 7 county post offices annually. Wasco County is a county located in the U.S. state of Oregon. As of the 2010 census, the population was 25,213. Its county seat is The Dalles. The county is named for a local tribe of Native Americans, the Wasco, a Chinook tribe who lived on the south side of the Columbia River. Wasco County comprises the The Dalles, OR Micropolitan Statistical Area."