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.
List of U.S. Highways in Utah
The U.S. Highways in Utah are painted by the Utah Department of Transportation (UDOT). The United States Numbered Highway System is a nationwide system with only a small portion of its routes entering Utah. Originally, the State Road Commission of Utah, created on March 23, 1909 was responsible for maintenance, but these duties were rolled into the new UDOT in 1975. There are of U.S. Highways in the state. The longest is U.S. Route 89 at and the shortest is U.S. Route 89A at . Five former U.S. Highways exist in the state of Utah, all of which have been replaced by current interstate and U.S. Highways, with the most recent change being U.S. Route 666 redesignated as U.S. Route 491 in 2003.