Sea Isle City is a city in Cape May County, New Jersey, United States. It is part of the Ocean City Metropolitan Statistical Area. As of the 2010 United States Census, the city's population was 2,114, reflecting an decline of 721 (-25.4%) from the 2,835 counted in the 2000 Census, which had in turn increased by 143 (+5.3%) from the 2,692 counted in the 1990 Census. Visitors raise the population to as much as 40,000 during the peak summer season from Memorial Day to Labor Day. Sea Isle City is located on Ludlam Island, which also contains part of Dennis Township.
Sea Isle City was originally incorporated as a borough on May 22, 1882, from portions of Dennis Township, based on the results of a referendum held six days earlier. The borough was reincorporated on March 31, 1890. On April 30, 1907, the area was reincorporated as the City of Sea Isle City, based on the results of a referendum held on April 20, 1907.