 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.