The Pelham Islands are a group of islands in western Long Island Sound that belonged to Thomas Pell in the 17th century. The islands, and most of the surrounding area, were purchased from the Siwanoy Indians by Pell in 1654, creating Pelham Manor. This large tract of land would eventually become the present-day Town and Village of Pelham and Pelham Manor, Town of Eastchester, cities of New Rochelle and Mount Vernon in Westchester County, and the Pelham Bay and Eastchester neighborhoods of the Bronx in New York City.

City Island is a neighborhood in the northeastern Bronx in New York City, located on an island of the same name approximately 1.5 miles (2.4 km) long by 0.5 miles (0.80 km) wide. City Island is located at the extreme western end of Long Island Sound, south of Pelham Bay Park, and east of Eastchester Bay.