U.S. Route 9 (US 9) is a north–south United States Numbered Highway in the states of Delaware, New Jersey, and New York in the Northeastern United States. It is one of only two U.S. Highways with a ferry connection ; the other is US 10. US 9 is signed east–west in Delaware and north–south on the rest of its route. The southern terminus of the route is in Laurel, Delaware, at an intersection with US 13, while the highway's northern terminus is at a junction with Interstate 87 (I-87) in Champlain, New York, where the old roadway continues north as the unsigned New York State Route 971B (NY 971B), which ends in a cul-de-sac just short of the Canadian border.

The Cape May–Lewes Ferry is a ferry system in the United States that traverses a 17-mile (27 km) crossing of the Delaware Bay connecting North Cape May, New Jersey with Lewes, Delaware. The ferry constitutes a portion of U.S. Route 9 and is the final crossing of the Delaware River-Delaware Bay waterway before it meets the Atlantic Ocean. It is only one of two direct crossings between Delaware and New Jersey, the other being the Delaware Memorial Bridge