There are 5 US Post Offices in Waller County serving a total of 27,464 residents equating to 5,493 residents per post office. It's estimated that approximately 43,836 packages are handled across the 5 county post offices annually. Waller County is a county in the U.S. state of Texas. As of the 2010 census, the population was 43,205. Its county seat is Hempstead. The county was named for Edwin Waller, a signer of the Texas Declaration of Independence and first mayor of Austin. Waller County is included in the Houston-The Woodlands-Sugar Land, TX Metropolitan Statistical Area.