Interstate 37 (I-37) is a Interstate Highway located within the southern portion of the U.S. state of Texas. The highway was first designated in 1959 as a route between Corpus Christi and San Antonio. Construction in the urban areas of Corpus Christi and San Antonio began in the 1960s and the segments of the Interstate Highway in rural areas were completed by the 1980s. Prior to I-37, the route between Corpus Christi and San Antonio was served by a combination of State Highway 9 (SH 9) from Corpus Christi to Three Rivers and U.S. Route 281 (US 281) from Three Rivers to San Antonio. As a result of the construction of I-37, SH 9 was removed from the State Highway System.