- Western Terminus:
- Midtown Tunnel (I-495) in Queens
- Eastern Terminus:
- Middle Country Road (NY 25) in Calverton
- 59.01 miles
- Queens, Nassau, Suffolk
NY 25A is the northernmost major east/west route on Long Island. It begins as 21 Street and Jackson Avenue at the Midtown Tunnel (I-495). Jackson Avenue ends at Queens Boulevard (NY 25), where Northern Boulevard begins. Northern Boulevard runs east through Queens and Nassau. At the Nassau-Suffolk county line, Northern Boulevard ends and NY 25A is routed to the north along Harbor Road through Cold Spring Harbor. Harbor Road becomes Main Street, which runs through Cold Spring Harbor and Huntington. After Huntington, Main Street becomes Fort Salonga Road, which later becomes Saint Johnland Road. NY 25A is multiplexed with NY 25 as Main Street in Smithtown. After NY 25 and NY 25A split, NY 25A is called North Country Road, in addition to some sections that have no name. As one proceeds farther east, NY 25A is called Hulse Avenue. The last section of NY 25A is Parker Road, which cuts to the south and ends at NY 25 in Calverton. Many years ago, instead of cutting south on Parker Road, NY 25A extended farther east along Sound Avenue and ended at NY 25 in Mattituck.