In 1819, City Island was annexed to the town of Pelham, Westchester County. It narrowly voted to become a part of New York City in 1895, in exchange for a new bridge to the mainland, and was consolidated as part of the Bronx in 1898. The island continued to host harbor defenses through the early 20th century. In the mid-20th century, City Island developed as a shipbuilding community, before becoming a daytrippers' destination. City Island has generally remained sparsely developed with a suburban feel. A 43-unit condo complex called On the Sound, built in 2015, was the first major residential project on the island since around 2000.
