Philadelphia is a town in Jefferson County, New York, United States. The population was 1,947 at the 2010 census,  down from 2,140 at the 2000 census. The town contains a village also called Philadelphia .
The Philadelphia Zoo, located in the Centennial District of Philadelphia, on the west bank of the Schuylkill River, was the first true zoo in the United States. It was chartered by the Commonwealth of Pennsylvania on March 21, 1859, but its opening was delayed by the Civil War until July 1, 1874.