There are 10 US Post Offices in Williams County serving a total of 39,078 residents equating to 3,908 residents per post office. It's estimated that approximately 62,373 packages are handled across the 10 county post offices annually. Williams County is a county located in the U.S. state of Ohio. As of the 2010 census, the population was 37,642. Its county seat is Bryan. The county was created in 1820 and later organized in 1824. It is named for David Williams, one of the captors of John Andr\u00e9 in the American Revolutionary War."