63034 -- U.S. ZIP code Municipality (1990): FLORISSANT, Missouri All ZIPs for this municipality (1990): 63031 63033 63034 Population (2000): 16803 Housing Units (2000): 5896 Land area (2000): 18.542901 sq. miles (48.025891 sq. km) Water area (2000): 0.006067 sq. miles (0.015714 sq. km) Total area (2000): 18.548968 sq. miles (48.041605 sq. km) Located within: Missouri (MO) Location: 38.832863 N, 90.290515 W