as their father's executors. John Mason built a mansion on the island around 1796 and planted crops for sale as well as gardens. He was an active member of the Agricultural Society of Georgetown and the Columbia Agricultural Society of Washington, and able to manufacture almost everything needed for home consumption (including cotton) on the island. He also entertained lavishly on the island, 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. In 1809 John Mason secured a charter for a turnpike to connect his ferry landing with the Washington-Alexandria turnpike that Congress had chartered the previous year (and which would follow what became U.S. Route 1 and compete with his ferry for traffic). 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operating a ferry between Georgetown and the Virginia shore until construction of the Aqueduct Bridge in 1843 (superseded by the Key Bridge in 1923), as well as from 1817 until 1838 serving as the last president of the Potowmack Company (founded in 1774 with George Washington as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). 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. 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. The first retrocession attempt was in 1804, and another major failed attempt occurred in 1824. However, by 1831, water stagnation caused the Mason family to move from the island. (Through his ownership, John Mason, who opposed retrocession, also had a Georgetown residence at the corner of 25th Street, L Street and Pennsylvania Avenue, which became the site of Columbia Hospital in 1932). In 1842, then elderly John Mason sold the island to John Carter. 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