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.
U.S. Route 40 in Maryland
U.S. Route 40 (US 40) in the U.S. state of Maryland runs from western Maryland to Cecil County in the state's northeastern corner. With a total length of over , it is the longest numbered highway in Maryland. Almost half of the road overlaps or parallels with Interstate 68 or Interstate 70, while the old alignment is generally known as U.S. Route 40 Alternate, U.S. Route 40 Scenic, or Maryland Route 144. West of Baltimore, in the Piedmont and 
Appalachian Mountains / Blue Ridge region of the Western Maryland panhandle of the small state, the portions where it does not overlap an Interstate highway are mostly two-lane roads. The portion northeast of Baltimore going to Wilmington, in northern Delaware and Philadelphia in southeastern Pennsylvania before crossing the Susquehanna River at the north end of the Chesapeake Bay, is a four-lane divided highway, known as the Pulaski Highway (named for American Revolutionary War (1775-1783) foreign military volunteer of Polish cavalry officer Casimir Pulaski, 1745-1779).