Prior to being the home of the Theodore Roosevelt Memorial, the island across the Potomac from Georgetown was known as Analostan and had a number of uses since the area's settlement. Military maps and accounts reveal that the island was taken in its entirety by the Mason family farm, whose grounds extended from a manor house built toward the island's southern end. Archaeologists working for the Civilian Conservation Corps during the Depression discovered that the land was primarily used for gentleman farming and found evidence of extensive gardening running the island's length. During the Civil War, federal troops occupied the island and used it as a bivouac, destroying much of the island's improvements. Abandoned after the war, the forest soon reclaimed much of the island and it went into federal receivership until the establishment of the Roosevelt Memorial.
This section of the river had historically been prone to shoaling as the velocity of the Potomac decreases as it spreads out to reach the coastal plain. Mason's causeway and bridge, which he built at the upstream end of the island for access to the Virginia shore, had a lasting effect on the shape of the island and extent of the surrounding wetlands, as the island is significantly longer and slenderer than it was two centuries previously.