The Interstate Highways in Texas are all owned and maintained by the U.S. state of Texas. The Texas Department of Transportation (TxDOT) is the agency responsible for the day-to-day maintenance and operations of the Interstate Highways in Texas. The Interstate Highway System in Texas covers and consists of twelve primary routes, seven auxiliary routes and Interstate 35 (I-35) which is split into two branches, I-35E and I-35W, that provide access to both Fort Worth and Dallas. The longest segment of Interstate Highway in Texas is I-10 at ; the shortest is I-110 at .
The construction of the Interstate Highway System in Texas began well before these routes were designated as Interstate Highways. A stretch of I-45 between Galveston and Houston was opened in 1951, eight years before it was designated I-45. It was also the first urban expressway in Texas. In 1962, of I-35 opened in Bexar County, the first section of Interstate Highway to open from county line to county line in a large metropolitan area. Portions of I-10 west of San Antonio took much longer to complete due to the vast open spaces and lack of nearby labor. The majority of the construction of this section of I-10 occurred in the 1970s and 1980s and was complete by the early 1990s. The section east of San Antonio was completed 20 years earlier in 1972. The opening of a section of I-27 in 1992 completed the Interstate Highway System in Texas.
Planning is ongoing for a proposed extension of I-69 southward from its original terminus in Indiana through Texas to the United StatesâÂÂMexico border. If complete as planned, I-69 will extend about across Texas, from the Louisiana state line in the TexarkanaâÂÂShreveport area to South Texas. The first portion was approved in 2011, with signage posted December 6, 2011.