There are 4 US Post Offices in Frio County serving a total of 17,506 residents equating to 4,377 residents per post office. It's estimated that approximately 27,942 packages are handled across the 4 county post offices annually. Frio County is a county located in the U.S. state of Texas. As of the 2010 census, its population was 17,217. The county seat is Pearsall. The county was created in 1858 and later organized in 1871. Frio is named for the Frio River, whose name is Spanish for \"cold\"."