There are 11 US Post Offices in Fremont County serving a total of 39,701 residents equating to 3,609 residents per post office. It's estimated that approximately 63,367 packages are handled across the 11 county post offices annually. Fremont County is a county located in the U.S. state of Wyoming. As of the 2010 census, the population was 40,123. Its county seat is Lander. The county was founded in 1884 and is named for John C. Fr\u00e9mont, a general, explorer, and politician. It is roughly the size of the state of Vermont. Fremont County comprises the Riverton, WY Micropolitan Statistical Area."