Interstate 40 (I-40) is an Interstate Highway in Oklahoma that runs 331 miles (533 km) across the state from Texas to Arkansas. West of Oklahoma City, it parallels and replaces Old US-66, and east of Oklahoma City, it parallels US-62, 266, and 64. Cities along the route include Erick, Sayre, Elk City, Clinton, Weatherford, El Reno, Oklahoma City, Shawnee, Okemah, Henryetta, Checotah, and Sallisaw.