There are 8 US Post Offices in Natrona County serving a total of 49,533 residents equating to 6,192 residents per post office. It's estimated that approximately 79,060 packages are handled across the 8 county post offices annually. Natrona County is a county located in the U.S. state of Wyoming. As of the 2010 census, the population was 75,450, making it the second-most populous county in Wyoming. Its county seat is Casper. Natrona County comprises the Casper, WY Metropolitan Statistical Area. In 2010, the center of population of Wyoming was located in Natrona County, near Alcova."