 Philadelphia remained the nation's largest city until being overtaken by New York City in 1790; the city was also one of the nation's capitals during the revolution, serving as temporary U.S. capital while Washington, D.C. was under construction.In the 19th century, Philadelphia became a major industrial center and a railroad hub.The city grew from an influx of European immigrants, most of whom came from Ireland, Italy and Germany—the three largest reported ancestry groups in the city .