Interstate 10 (I-10) is the major east–west Interstate Highway in the Southern United States. In the U.S. state of Texas, it runs east from Anthony, at the border with New Mexico, through El Paso, San Antonio and Houston to the border with Louisiana in Orange, Texas. At just under 880 miles (1,420 km), the Texas segment of I-10, maintained by the Texas Department of Transportation, is the longest continuous untolled freeway in North America that is operated by a single authority, a title formerly held by Ontario Highway 401. It is also the longest stretch of highway with a single designation within a single state. Mile marker 880 and its corresponding exit number in Orange, Texas are the highest numbered mile marker and exit on any freeway in North America, with Interstate 5 in California