Region
United States
78
China
2
Colorado
2
Kentucky
2
Outer space
2
Pueblo
2
Richmond
2
Russia (Federation)
2
Africa
1
Colorado River Watershed (Colo.-Mexico)
1
Developing countries
1
Everglades
1
Everglades (Fla.)
1
Florida
1
Klamath River Watershed (Or. and Calif.)
1
Louisiana
1
Mars (Planet)
1
Mexico, Gulf of
1
Nigeria
1
North America
1
Polar regions
1
Russia
1
Solar system
1
Virginia
1