The Texas Department of Transportation (TxDOT) is the state agency responsible for the day-to-day operations and maintenance of the system.

The Old San Antonio Road, also known as the El Camino Real, is the oldest highway in the United States, first being blazed in 1691.

Administrative control of the department was given to a three-member commission appointed by the governor for two-year terms.

On June 21, 1917, the commission conducted its first public hearing to solicit input on potential highway routes.

In 1957, the state began receiving federal funding for the construction of the Interstate Highway System.

In 1997, the Texas Turnpike Authority was merged with TxDOT and independently, the North Texas Turnpike Authority became responsible for toll projects in Collin, Dallas, Denton, and Tarrant counties.

A 50-mile (80 km) stretch of the Gulf Freeway (I-45) between Galveston and Houston was opened in 1951, eight years before it was designated I-45.

[5] Portions of I-10 west of San Antonio took much longer to complete due to the vast open spaces and lack of nearby labor.

[7] The opening of a 6-mile (10 km) section of I-27 in 1992 completed the Interstate Highway System in Texas.

[6] Construction is ongoing for an extension of I-69 southward from its original terminus in Indiana through Texas to the Mexican border.

Highways that are built to freeway standards include US 75 and US 80 in Dallas, US 59 and US 290 in Houston, and US 90 and US 281 in San Antonio.

Thus, spurs and loops are not related to similarly numbered main state highways.

The first loops and spurs were defined in 1939; prior to that, the roadways had been suffixed segments of the main state highways of which they branched.

In 1991, all the business routes were assigned official designations, and their former loop and spur numbers were eliminated.

After the city or county acquires right-of-way, TxDOT builds and maintains the road.

Several toll roads have one-way frontage roads—not necessarily continuous—with state highway numbers.