There are 8 US Post Offices in Seneca County serving a total of 32,567 residents equating to 4,071 residents per post office. It's estimated that approximately 51,981 packages are handled across the 8 county post offices annually. Seneca County is a county located in the U.S. state of New York. As of the 2010 census, the population was 35,251. The primary county seat is Waterloo, moved from the original county seat of Ovid in 1819. It became a two-shire county in 1822, using both locations as county seats although the majority of Seneca County administrative offices are in Waterloo. Therefore, most political sources only list Waterloo as the county seat. The county's name is from the Iroquois (Seneca) that occupied part of the region. Seneca County comprises the Seneca Falls, NY Micropolitan Statistical Area, which is also included in the Rochester-Batavia-Seneca Falls, NY Combined Statistical Area."