Region
West (U.S.)
United States
10
Colorado River (Colo.-Mexico)
4
Colorado River Watershed (Colo.-Mexico)
4
Colorado
3
California
2
Canada, Western
2
Santa Fe National Historic Trail
2
Animas River (Colo. and N.M.)
1
Arizona
1
British Columbia
1
Colorado Plateau
1
Colorado River Region (Colo.-Mexico)
1
Colorado River Valley (Colo.-Mexico)
1
Columbia River
1
Columbia River Watershed
1
Glen Canyon Dam (Ariz.)
1
Gold King Mine (San Juan County)
1
Great Plains
1
Green River (Wyo.-Utah)
1
Green River Watershed (Wyo.-Utah)
1
Hawaii
1
Missouri River
1
Missouri River Watershed
1
Nebraska
1
Nevada
1
Oregon
1
Pacific Coast (North America)
1
Powell, Lake (Utah and Ariz.)
1
Rio Grande (Colo.-Mexico and Tex.)
1
Rocky Mountains Region
1
Sacramento River (Calif.)
1
Saint Helens, Mount (Wash.)
1
San Joaquin River (Calif.)
1
Utah
1
Yuma Valley
1
Yuma Valley (Ariz.)
1