Interstate 66, commonly known as I-66, is a major east-west highway in the United States. It runs for approximately 75 miles, connecting the city of Washington, D.C. to Warrenton, Virginia. The highway serves as a vital route for commuters and travelers, facilitating access to various towns and attractions along the way. I-66 was officially opened in 1964 and is part of the larger Interstate Highway System. The highway features both regular and high-occupancy vehicle (HOV) lanes, promoting carpooling and reducing traffic congestion. It plays a crucial role in the transportation network of the Northern Virginia region.