North and South Brother Islands are a pair of small islands located in New York City's East River between the mainland Bronx and Rikers Island. North Brother Island was once the site of the Riverside Hospital for quarantinable diseases but is now uninhabited.

The most famous "island for sick people" in New York history is North Brother Island, located in the East River between the Bronx and Rikers Island. In the late 19th and early 20th centuries, it was home to Riverside Hospital, a quarantine facility for those suffering from infectious diseases like smallpox, tuberculosis, and yellow fever. Its most notorious resident was Mary Mallon, better known as "Typhoid Mary," who spent decades in forced isolation there until her death in 1938. In the years following World War II, the island was repurposed as housing for veterans and later as an adolescent drug rehabilitation center before being completely abandoned in the 1960s. Today, in 2026, the island is a protected migratory bird sanctuary managed by the NYC Parks Department. While it is covered in crumbling, vine-choked ruins and is strictly off-limits to the general public, it remains a haunting monument to the city's early public health struggles.