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.
Arkansas Highway System
Arkansas first established a statewide state highway system in 1924. This system labeled its routes in a "letter-number number" system such as A-11. The roads were all designated as "State Road l-nn" prior to the creation of the U.S. Numbered Highway System. Upon creation of the Harrelson Road Law, the US Route system came to Arkansas and the system was renumbered. This system has generally remained in place, with the major addition of the Interstate Highway System in 1965. The original system had just over 100 routes, mostly dirt paths that became unpassable after rain. Arkansas began using the same pavement techniques used for Dollarway Road, which was the longest continuous concrete pavement in the United States when completed in 1913.
These routes were signed with white cut-out shapes of Arkansas, which said "State Road" in addition to the route number. In the 1950s, the Araknsas Highway Department removed the "State Road" and instead printed "ARKANSAS" on top of the shields, with a line underneath the state name. The shields were changed to the current format circa 1971, though all numbers were within square shields. A wider sign was created later to allow three-digit routes to use the same font size as two-digit routes.