15501 -- U.S. ZIP code Municipality (1990): SOMERSET, Pennsylvania All ZIPs for this municipality (1990): 15501 Population (2000): 17155 Housing Units (2000): 8150 Land area (2000): 138.122616 sq. miles (357.735919 sq. km) Water area (2000): 0.540325 sq. miles (1.399435 sq. km) Total area (2000): 138.662941 sq. miles (359.135354 sq. km) Located within: Pennsylvania (PA) Location: 40.028470 N, 79.110503 W