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.
Massachusetts Route 28
The original form of Route 28 was as a New England interstate route established in 1922 to run from Buzzards Bay to New Hampshire. The route itself was overlaid on several early turnpike roads constructed in the early 19th century. Except for an extension into Cape Cod in 1926, the overall highway layout and routing is largely unchanged from its original design. Route 28 has been realigned in several places when newer, higher quality roads were built. At a length of nearly , Route 28 is the longest state-numbered highway in Massachusetts, and the second-longest highway, behind U.S. Route 20.