List of Interstate Highways in Washington
Interstate 90 (I-90) is the longest primary Interstate Highway in Washington, which connects Seattle to Spokane and the Idaho border, measuring , while I-82, connecting the Oregon border city of Umatilla to Elensburg via Yakima, is the shortest at . The longest auxiliary Interstate Highway in Washington is I-405, a bypass of Seattle through the Eastside, at , and the shortest is I-705, a spur into downtown Tacoma, at . One route, I-605, has been proposed over the years to form another Eastside bypass, however there are no plans to construct this fifth auxiliary route.
After passage of the Federal Aid Highway Act of 1956, which formed the Interstate Highway System, the American Association of State Highway Officials had approved I-5 and I-90 across Washington on August 17, 1957. I-82 was approved on October 17, 1957, two months after I-5 and I-90, as part of a addition to the Interstate Highway System.
Philadelphia and Lancaster Turnpike
The Philadelphia and Lancaster Turnpike, first used in 1795, is the first long-distance paved road built in the United States, according to engineered plans and specifications. It links Lancaster, Pennsylvania, and Philadelphia at 34th Street, stretching for sixty-two miles. However, the western terminus was actually at the Susquehanna River in Columbia. The route is designated Pennsylvania Route 462 from the western terminus to US 30, where that route takes over for the majority of the route. The US 30 designation ends at Girard Avenue in the Parkside neighborhood of Philadelphia, where State Route 3012 takes it from there to Belmont Avenue. At Belmont Avenue, State Route 3005 gets the designation from Belmont Avenue until the terminus at 34th Street.