Following the Hudson River closely as a busy surface road through the many suburban river villages and past National Historic Landmarks such as Sunnyside and Kykuit, US 9 becomes the Croton Expressway between Croton-on-Hudson and Peekskill. That section ends at the Annsville Circle junction with US 6 and 202, where US 9 returns to two-lane status as it follows the old post road inland, away from the river. At Fishkill, the road passes the historic Van Wyck Homestead Museum and it becomes a six-lane divided strip until reaching the Poughkeepsie city limit. It then narrows to a four-lane divided strip which lasts until it intersects St. Andrews Rd, just north of the Hyde Park/Poughkeepsie town line where it returns to two-lane status as it goes through Hyde Park and past its historic sites.