St. Clement's Island in the Potomac River is the site where Maryland's first colonists landed on March 23, 1634, then held a Mass of thanksgiving two days later, an event long associated with the first Roman Catholic Mass in the British-American colonies and remembered as part of Maryland Day. The settlers used the island as a temporary base while arranging land with the Yaocomico people for a permanent settlement. Later known for many years as Blackistone Island, it passed through colonial ownership, was altered heavily by U.S. Navy use in 1919, became a state park in 1962, regained its historic name in 1965, and remains a place of preservation, memorials, and recreation.