New York's 1st congressional district is a congressional district for the United States House of Representatives in eastern Long Island. It includes the eastern two-thirds of Suffolk County, including the northern portion of Brookhaven, as well as the entirety of the towns of Huntington, Smithtown, Riverhead, Southold, Southampton, East Hampton, and Shelter Island. The district encompasses extremely wealthy enclaves such as the Hamptons, middle class suburban towns such as Selden, Centereach, and Lake Grove, working-class towns such as Riverhead and rural farming communities such as Mattituck and Jamesport on the North Fork. The district currently is represented by Republican Nick LaLota who lives in Amityville, outside of the district.

Suffolk County is the easternmost county in the U.S. state of New York. It is bordered to its west by Nassau County, to its east by Gardiners Bay and the Atlantic Ocean, to its north by Long Island Sound, and to its south by Great South Bay. The county is part of the Long Island region of the state, of which it comprises the eastern two-thirds.