15478 -- U.S. ZIP code Municipality (1990): SMITHFIELD, Pennsylvania All ZIPs for this municipality (1990): 15478 Population (2000): 6473 Housing Units (2000): 2622 Land area (2000): 58.227925 sq. miles (150.809628 sq. km) Water area (2000): 0.018802 sq. miles (0.048697 sq. km) Total area (2000): 58.246727 sq. miles (150.858325 sq. km) Located within: Pennsylvania (PA) Location: 39.791113 N, 79.812476 W