Region
Arizona
17
Colorado
15
Utah
13
Oklahoma
10
San Juan Basin (N.M. and Colo.)
10
Kentucky
9
New Mexico
8
Ozark Mountains Region
7
Wyoming
7
Southwest, New
6
Kansas
5
Massachusetts
5
Salt Lake County
4
Great Plains
3
Maine
3
Nevada
3
Powder River Basin (Wyo. and Mont.)
3
Texas
3
California
2
Campbell County
2
Cochise County
2
Colorado River Watershed (Colo.-Mexico)
2
Denver Region
2
Front Range (Colo. and Wyo.)
2
Graham County
2
Kaiparowits Plateau Region
2
Maricopa County
2
Mississippian Plateau
2
Missouri
2
North Carolina
2
Phoenix Region
2
Pima County
2
Tucson
2
Virginia
2
Washington County
2
Alaska
1
Allegheny County
1
Allegheny County (Pa.)
1
Alton-Kolob Coalfields Region
1
Ambrosia Lake
1
Appalachian Region
1
Ardmore Quadrangle
1
Arkansas
1
Baca County
1
Boston
1
Boyd County
1
Breathitt County
1
Cape Cod
1
Cape Hatteras National Seashore
1
Cape Hatteras National Seashore (N.C.)
1
more ...