There are 8 US Post Offices in Westmoreland County serving a total of 19,060 residents equating to 2,383 residents per post office. It's estimated that approximately 30,422 packages are handled across the 8 county post offices annually. Westmoreland County is a county located in the Northern Neck of the Commonwealth of Virginia. At the 2010 census, the population was 17,454. Its county seat is Montross."