Gloucester City is a city in Camden County, New Jersey, United States. As of the 2010 United States Census, the city's population was 11,456, reflecting a decline of 28 from the 11,484 counted in the 2000 Census, which had in turn declined by 1,165 from the 12,649 counted in the 1990 Census. It is located directly across the Delaware River from Philadelphia and the Port of Philadelphia.Gloucester City was incorporated by an act of the New Jersey Legislature on February 25, 1868, from the remaining portions of Union Township, which was then dissolved. Additional territory was annexed in 1925 from Centre Township and in 1927 from Haddon Township. The city's name derives from Gloucester, England.Gloucester City is known for its Irish American population, which was ninth-highest in the United States by percentage in the 2000 Census.