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.
Taconic State Parkway
The Taconic State Parkway (often called the Taconic or the TSP and known administratively as New York State Route 987G or NY 987G) is a divided highway between Kensico Dam and Chatham, the longest parkway in the U.S. state of New York. It follows a generally northward route midway between the Hudson River and the Connecticut and Massachusetts state lines, along the Taconic Mountains. Its southernmost are a surface road; from the junction with the Sprain Brook Parkway northward it is a limited-access highway. It has grade-separated interchanges from that point to its northern terminus; in the three northern counties, there are also at-grade intersections, many with closed medians, allowing only right-in/right-out turns. It is open only to passenger vehicles, as with other parkways in New York, and maintained by the state Department of Transportation (NYSDOT), the fourth agency to have that responsibility.