List of Interstate Highways
There are 70 primary Interstate Highways in the Interstate Highway System, a network of controlled-access freeways in the United States. They are assigned one- or two-digit route numbers, whereas their associated "auxiliary" Interstate Highways receive three-digit route numbers. Typically, odd-numbered Interstates run south-north, with lower numbers in the west and higher numbers in the east; even-numbered Interstates run west-east, with lower numbers in the south and higher numbers in the north. Highways whose route numbers are divisible by "5" usually represent major coast-to-coast or border-to-border routes (ex. I-10 travels from Santa Monica, California, to Jacksonville, Florida, traveling from the Pacific to Atlantic oceans). Additionally, auxiliary highways have their numbering system where a different number prefixes the number of its parent highway.
List of Interstate Highways in Texas
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 .