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. The borough was named for Hamburg, Germany.
According to the United States Census Bureau, the borough had a total area of 1.17 square miles (3.03 km2), including 1.15 square miles (2.96 km2) of land and 0.02 square miles (0.06 km2) of water (2.05%).
Hamburg borders the Sussex County municipalities of Franklin and Hardyston Township.
The 2010 United States Census counted 3,277 people, 1,364 households, and 884 families in the borough. The population density was 2,870.4 inhabitants per square mile (1,108.3/km2). There were 1,476 housing units at an average density of 1,292.9 per square mile (499.2/km2). The racial makeup was 91.27% (2,991) White, 2.01% (66) Black or African American, 0.24% (8) Native American, 2.04% (67) Asian, 0.00% (0) Pacific Islander, 1.80% (59) from other races, and 2.62% (86) from two or more races. Hispanic or Latino of any race were 6.87% (225) of the population.
Of the 1,364 households, 30.8% had children under the age of 18; 49.5% were married couples living together; 10.8% had a female householder with no husband present and 35.2% were non-families.