Today miles of trails through wooded uplands and swampy bottomlands honor the legacy of a great outdoorsman and conservationist.

[11] He also entertained lavishly on the island,[12] including a 1798 party to honor then-uncrowned Louis Philippe I, and an 1811 fete for his son John Murray Mason before he left to study in Paris.

[14] John Mason also diversified his income-producing activities, operating a ferry between Georgetown and the Virginia shore until construction of the Aqueduct Bridge in 1843 (superseded by the Key Bridge in 1923),[15][16] as well as from 1817 until 1838 serving as the last president of the Potowmack Company (founded in 1774 with George Washington as its first President and in order to deepen the Potomac's channel and build locks around the principal falls).

[17] Using federal funds and private funds raised by Georgetown merchants, a causeway from the Virginia shore to the island was constructed after debris from flooding in the winter of 1784 changed the Potomac River's main channel from the island's western side to the eastern side and increased silt which threatened the nearby Georgetown port.

[18][19] Alexandria merchants objected to the causeway and it proved a sticking point in their calls for retrocession of 26 square miles of land Virginia had given to establish the federal city as the century began.

[7] Four years later, Congress left retrocession to a referendum, which President James K. Polk authorized and Alexandria voters endorsed by a 763 to 222 vote on September 1, 1846 (despite opposition from the northern areas).

[7] Nonetheless, in 1854, the island again hosted an entertainment, this time given by the late John Mason's daughter Anna Maria (who had married Sydney Smith Lee in 1834) to mark a treaty opening Japan to foreign trade (Captain Lee having served under Commodore Matthew C. Perry on the voyage which resulted in the treaty).

[24] Union forces occupied the island, Mason's former mansion, and the rest of the formerly retroceded area on the night of May 23–24, hours after Virginia voters ratified secession.

Three federal units covered the three major trans-Potomac routes, and soon fortified the county as part of the military defenses of the nation's capital.

[26] Following President Lincoln's decision to allow African Americans to join the U.S. Army, the 1st United States Colored Infantry used the island to train its soldiers.

[28] Following the declaration of war against Spain in 1898, the island became a test site for a number of private experiments in electrical ignition of the explosives dynamite and joveite led by the chemist Charles Edward Munroe of Columbian University.

At one point opposite Georgetown, the Atlantic Seaboard fall line between the Piedmont and the Coastal Plain can be seen as a natural phenomenon.

Pedestrians can reach the parking lot and footbridge by following the Mount Vernon Trail south from the intersection of Langston Boulevard and North Lynn Street in Rosslyn, near Key Bridge.

[33] Several hiking trails provide access to the memorial and a variety of the island's natural habitats, including a boardwalk through a swampy and marshy area.