There are 10 US Post Offices in Fayette County serving a total of 18,407 residents equating to 1,841 residents per post office. It's estimated that approximately 29,380 packages are handled across the 10 county post offices annually. Fayette County is a county located in the U.S. state of Iowa. As of the 2010 census, the population was 20,880. The county seat is West Union."