There are 7 US Post Offices in Dinwiddie County serving a total of 14,541 residents equating to 2,077 residents per post office. It's estimated that approximately 23,209 packages are handled across the 7 county post offices annually. Dinwiddie County is a county located in the Commonwealth of Virginia. As of the 2010 census, the population was 28,001. Its county seat is Dinwiddie. Dinwiddie County is part of the Richmond, VA Metropolitan Statistical Area."