In the late 1990s, I-540 was extended into Northwest Arkansas. It had been planned since the 1970s as a bypass of U.S. Highway 71. The first section, between Alma and Mountainburg was known as Arkansas Highway 540. Originally, the Arkansas State Highway and Transportation Department (AHTD) asked the American Association of State Highway and Transportation Officials (AASHTO), who are in charge of Interstate and U.S. Highway route numbering, to allow the Interstate segment between Fort Smith and Bentonville to be named I-49, in order to emphasize plans to extend the route from Shreveport, Louisiana, through Arkansas to Kansas City, Missouri. AASHTO refused and the route opened on January 8, 1999, as a northern extension of I-540. On October 18, 2013, AASHTO approved AHTD's application to designate I-49 across the state, specifically allowing the state to renumber I-540 as I-49. The northern section of I-540 was renumbered I-49 in April 2014.