El Paso County was created by the Texas Legislature on January 3, 1850, and San Elizario, then the most prosperous and largest town in the area, became the first county seat. The building served as the first jail, with the Commissioners Court approving the purchase of two prefabricated iron cells manufactured in Chicago, and those cells remain in the building. The front of the building may have formed part of the original Presidio wall, and the jail remained in service until the 1940s. According to Sheriff Pat Garrett and local legend, this was the only jail Billy the Kid ever broke into, when in December 1876 he reportedly freed his friend Melquiades Segura after convincing Sheriff Charles Kerber in the dark that he was a Texas Ranger delivering a prisoner, then overpowering the sheriff without gunfire and escaping quickly into Mexico.