(Created 1858, Organized 1871) Home of Pachal Indians before Spaniards arrived in Mexico (1519). First area explorer was Alonso de Leon, 1690, searching for Fort St. Louis founded by La Salle.
Upper Presidio Road--artery of travel from Saltillo, Mexico, to East Texas--crossed Frio River and became a King's Highway , 1720. Frio Town, first county seat, was located on the road, over which Santa Anna marched to destroy defenders of the Alamo in 1836.
County took name from Frio (a Spanish word which means "cold") River. The county seat moved to Pearsall, 1883. Jail, built 1884, is the oldest building in town.