Loop 368 follows the original routing of US 81 on the northeast side of San Antonio. US 81 was first designated along this stretch in 1927 and is the basis of the name Austin Highway, as US 81 was the primary route from San Antonio to Austin at the time. On August 1, 1962, when US 81 was rerouted onto the freeway to the east, the old segment was designated as Loop 368, but signed as Business U.S. 81. The route was signed as Loop 368 after US 81 was decommissioned south of Fort Worth in 1991.
