Region
United States
135
Colorado
13
Alaska
7
National Petroleum Reserve
5
Florida
4
Menominee County (Wis.)
4
Menominee Indian Reservation (Wis.)
4
National Petroleum Reserve (Alaska)
4
Sacramento Metropolitan Area (Calif.)
4
South Carolina
4
West (U.S.)
3
Arkansas
2
California
2
Louisiana
2
Minnesota
2
New Mexico
2
Antioquia (Department)
1
Appalachian Basin
1
Arizona
1
Balkan Peninsula
1
Belly River Region (Mont. and Alta.)
1
Calaveras County
1
Canadian Forces Base Borden (Ont.)
1
Cascade Range
1
Central America
1
Chaffee County
1
China
1
Chocó
1
Colombia
1
Columbia River Watershed
1
Corpus Christi Bay
1
Dolores County
1
Earth (Planet)
1
East Asia
1
Fort Collins
1
Fort Huachuca
1
Garfield County
1
Golden
1
Goshute Reservation (Nev. and Utah)
1
Great Plains
1
Gunnison County
1
Humboldt County
1
Illinois
1
Jamestown
1
Kilauea Volcano (Hawaii)
1
Klamath River Watershed (Or. and Calif.)
1
Lake County
1
Livengood Region
1
Logan County
1
Long Valley Region (Mono County)
1
more ...