63304 -- U.S. ZIP code Municipality (1990): SAINT CHARLES, Missouri All ZIPs for this municipality (1990): 63301 63303 63304 Population (2000): 38383 Housing Units (2000): 12988 Land area (2000): 44.201385 sq. miles (114.481057 sq. km) Water area (2000): 0.295112 sq. miles (0.764336 sq. km) Total area (2000): 44.496497 sq. miles (115.245393 sq. km) Located within: Missouri (MO) Location: 38.729260 N, 90.653323 W