Interstate 66 (I-66) is an Interstate Highway in the eastern United States. As indicated by its even route number, it runs in an east–west direction. Its current western terminus is in Middletown, Virginia, at an interchange with Interstate 81; its eastern terminus is in Washington, D.C., at an interchange with U.S. Route 29. Because of its terminus in the Shenandoah Valley, the highway was once called the "Shenandoah Freeway." Much of the route parallels U.S.