One of the most unique features of State Line Avenue is the only U.S. Post Office sitting in two states. The Post Office has two zip codes, 71854 for Texarkana, Arkansas and 75501 for Texarkana, Texas. Built in 1932-33 the structure features a base of pink granite from Texas and walls of limestone from Arkanasas. The Federal Building has long been a favorite point of interest. When you are ready for a photo so large it takes two states, come pose on Photographer’s Island at 500 State Line Avenue!*