New Philadelphia is a city in the U.S. state of Ohio and is both the largest city in and county seat of Tuscarawas County. It is located south of Cleveland and northeast of Columbus on the Tuscarawas River. It was established in 1804. Because of the presence of coal and clay, early industry in the city centered on mining interests and the manufacturing of steel, canned goods, roofing tile, sewer pipe, bricks, vacuum cleaners, stovepipes, carriages, flour, brooms, and pressed, stamped, and enameled goods. The population was 17,288 at the 2010 census.