Following the September Massacres, William migrated to America directly from France. He visited Boston, and spent some time in Brattleboro, Vermont, with the also newly arrived family of William Wells, who was looking to buy a farm there. In the Autumn of 1794, after visiting his parents in New York, William stayed for a while in Boston, spending time with the Unitarian minister Dr James Freeman, and visiting Freeman's Harvard classmate Dr William Bentley, Unitarian pastor of East Church, Salem; though, for several weeks at a time, in October and December, William was ill with a high fever, perhaps malaria. After recovering his health, William removed to the backwoods of Northumberland County, Pennsylvania, at Point township (now Northumberland borough) in February 1795. Here, William and his brother Henry bought a 284-acre plot of woodland, which they attempted to transform into a farm, later called "Fairhill", felling and uprooting trees, and obtaining lime to sweeten the soil by building their own lime kilns. Henry Priestley died 11 December 1795, possibly of malaria which he may have contracted after landing at New York.