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 parkway between Kensico Dam and Chatham, the longest in the U.S. state of New York. It follows a generally north–south route midway between the Hudson River and the Connecticut and Massachusetts state lines, much of its upper section along the westernmost flank of the Taconic Mountains. Its southernmost are a surface road; from the junction with the Sprain Brook Parkway northward it is a limited-access divided 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. Franklin D. Roosevelt, who had long envisioned a scenic road through the eastern Hudson Valley, was instrumental in making it a reality as a way to provide access to existing and planned state parks in the region. Its winding, hilly route was designed by landscape architect Gilmore Clarke to offer scenic vistas of the Hudson Highlands, Catskills and Taconic regions. The bridges and now-closed service areas were designed to be aesthetically pleasing. It has been praised for the beauty of not only the surrounding landscape and views it offers, but the way the road itself integrates with and presents them. It was completed in its present form in the early 1960s. In 2005, the entire highway, including its supporting structures, was listed on the National Register of Historic Places in recognition of its historic importance in the development of parkways in the 20th century, and Roosevelt's role in creating it. It is the second-longest continuous road listed on the Register after Virginia's Skyline Drive, and the longest limited-access highway. The parkway continues to provide access to several state parks, including Franklin D. Roosevelt State Park. It has also become an important regional artery, one of the primary routes to northern New England and upstate New York from New York City and Long Island. The southern sections, particularly in Westchester County, have become a commuter route into the city for residents who moved into towns that became suburbanized as a result of the parkway. The state and regional transportation planners