This island in the East River between Manhattan and Queens was first colonized by the Dutch in 1620, who named it Varckens Evlandt (Hogs Island). The English took over in 1665 and awarded the island to Captain John Manning (the sheriff of NYC at the time) and renamed it Manning's Island. When Manning died in 1685, the island was inherited by Manning's married stepdaughter, Mary Manningharn, wife of Robert Blackwell, and the island became Blackwell's Island. The Blackwell Family acquired the island in 1676 and The site was purchased by the city for medical and prison facilities in 1828. In 1921 it was renamed Welfare Island, reflecting the usage of the island as a dumping ground for society's unwanted.
In 1969, with many of the institutions on the island having been closed and abandoned, the New York State Urban Development unveiled a planned community for the island developed by the firm of Philip Johnson and John Burgee. In 1973, the island was renamed Roosevelt Island after Franklin Delano Roosevelt and in anticipation large granite monument to the former president planned (but never built) for the southern tip of the island.
The first phase of the development, Northtown, was largely completed in the 1970s. Northtown Phase II (to the north of Northtown Phase I) was completed in 1989. Southtown was started in 1998 and development continues as of this writing.
There are numerous sites on the web for further info on Roosevelt Island. Among them:
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