Hamburg is a borough in Sussex County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 3,277, reflecting an increase of 172 (+5.5%) from the 3,105 counted in the 2000 Census, which had in turn increased by 539 (+21.0%) from the 2,566 counted in the 1990 Census.
In 1753, when Sussex County was formed, the area of present-day Hamburg was part of New Town; on February 25, 1762, it became part of the newly established Hardyston Township. On April 8, 1793, when Vernon Township was formed from Hardyston, Hamburg was included within the boundaries of Vernon. In 1852, the boundary line was changed so that Hamburg was again in Hardyston Township. Hamburg was incorporated as a borough on March 19, 1920 from portions of Hardyston Township, based on the results of a referendum held on April 24, 1920.