There are 14 US Post Offices in Galveston County serving a total of 285,037 residents equating to 20,360 residents per post office. It's estimated that approximately 454,951 packages are handled across the 14 county post offices annually. Galveston County is a county in the U.S. state of Texas. As of the 2010 census, the population was 291,309. Its county seat is Galveston. League City is the most populous city in Galveston County; between 2000 and 2005 it surpassed Galveston as the county's largest city. The county was founded in 1838. Galveston County is part of the Houston-The Woodlands-Sugar Land, TX Metropolitan Statistical Area."