The Interstate Highway System in Texas covers 3,239.7 miles (5,213.8 km) 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.

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

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

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

[5] Planning is ongoing for a proposed extension of I-69 southward from its original terminus in Indiana through Texas to the United States–Mexico border.