After the Blackistone family took ownership in 1669, the island remained in the family for 162 years. It was taken over by the US Navy in 1919, at which time a landing strip and piers were built and the island's buildings and trees were removed. In 1962, the property was designated as a state park when it was leased from the Federal government and its name reverted to St. Clement's Island. The name change was made official by the Board of Geographic Names in 1965.