Roosevelt Island was first purchased in 1637. In 1796, Jacob Blackwell constructed the Blackwell House. Today, the Blackwell House is the sixth oldest house in New York City. In the 19th Century, there were hospitals and a prison on the island. The island was purchased by the city of New York. In 1900 the Queensboro Bridge started construction. It passed over the island, however it did not provide vehicular access. In 1930, a vehicular elevator was built. In 1955, the Welfare Island Bridge was opened. This allowed vehicular access from Queens. The vehicular elevator was shutdown and demolished in 1970. Architects Philip Johnson and John Burgee created a plan for apartment building housing 20,000 residents. The plan divided the island into three residential communities and discouraged automobiles. One year later, the island was renamed in honor of Franklin D. Roosevelt. Today, people can use the subway, tramway, or the Welfare Island Bridge to travel to the island. Approximately, 12,000 people live on Roosevelt Island.