On January 12, 1965, the Joseph Priestley House was designated a National Historic Landmark and it was added to the National Register of Historic Places (NRHP) on October 15, 1966. On August 1, 1994, the American Chemical Society named it the second National Historic Chemical Landmark; the dedication ceremony was attended by 75 Priestley descendants. In 1988, the Northumberland Historic District, including the Priestley House (which it describes as a "gem" and one of the finest Federal style buildings in central Pennsylvania), was listed on the NRHP. The district includes one other building already on the NRHP: the Priestley-Forsyth Memorial Library, which was built as an inn around 1820 and was owned by a great-grandson of the Priestleys in the 1880s. Today it serves as Northumberland's public library. The Joseph Priestley Memorial Chapel, which is a contributing structure in the historic district, was built in 1834 by his grandson, and is home to a Unitarian Universalist congregation that considers Priestley its founder.