20874 -- U.S. ZIP code Municipality (1990): DARNESTOWN, Maryland All ZIPs for this municipality (1990): 20874 20878 Population (2000): 49224 Housing Units (2000): 19187 Land area (2000): 19.573235 sq. miles (50.694445 sq. km) Water area (2000): 0.054345 sq. miles (0.140752 sq. km) Total area (2000): 19.627580 sq. miles (50.835197 sq. km) Located within: Maryland (MD) Location: 39.169859 N, 77.275645 W