South Amboy is a suburban city in Middlesex County, New Jersey, on the Raritan Bay. As of the 2010 United States Census, the city's population was 8,631, reflecting an increase of 718 (+9.1%) from the 7,913 counted in the 2000 Census, which had in turn increased by 50 (+0.6%) from the 7,863 counted in the 1990 Census.
South Amboy and Perth Amboy, across the Raritan River, are collectively referred to as The Amboys. Signage for exit 11 on the New Jersey Turnpike refers to "The Amboys" as a destination.
First settled by the Lenape Native Americans, who called the area around Perth Amboy by the name "Ompoge" (meaning "level ground"), the settlement ultimately became a key port for commerce between Lower New York Bay and Philadelphia, connected first by stagecoach and eventually by railroad. When settled by Europeans in 1684, the city was named New Perth in honor of James Drummond, Earl of Perth, one of the associates of a company of Scottish proprietaries. The Algonquian language name was corrupted to Ambo, or Point Amboy, and eventually a combination of the native and colonial names was used.
South Amboy has passed through three of the five types of New Jersey municipalities. It was first mentioned on May 28, 1782, in minutes of the Board of chosen freeholders as having been formed from Perth Amboy Township. It was formally incorporated as a township by the Township Act of 1798 on February 21, 1798. Over the next 90 years, portions split off to form Monroe Township (April 9, 1838), Madison Township (March 2, 1869; later renamed Old Bridge Township) and Sayreville Township (April 6, 1876; later Borough of Sayreville). As of February 25, 1888, South Amboy borough was formed, replacing South Amboy Township. On April 11, 1908, South Amboy was incorporated as a city, replacing South Amboy borough, confirmed by a referendum held on July 21, 1908.
South Amboy's strategic location as a transportation hub acted to its detriment in 1918 and 1950, when the town was heavily damaged by military explosives.