Washington is a borough in Warren County, New Jersey, United States. As of the United States 2010 Census, the borough population was 6,461. The borough is located in the eastern most region of the Lehigh Valley.
Washington was incorporated as a borough by an Act of the New Jersey Legislature on February 20, 1868, from portions of Washington Township.
Washington is located at 40°45′38″N 74°58′45″W / 40.760532°N 74.979231°W / 40.760532; -74.979231 (40.760532, -74.979231).