Region
United States
278
Colorado
164
Wyoming
70
Utah
57
Montana
55
Pennsylvania
50
West Virginia
36
Campbell County
29
Alaska
23
Illinois
23
Ohio
22
New Mexico
20
Kentucky
19
Powder River Basin (Wyo. and Mont.)
18
Oklahoma
17
Appalachian Region
14
Alabama
13
Carbon County
13
Virginia
11
Indiana
10
Kansas
9
Washington (State)
9
West (U.S.)
9
Tennessee
8
Rosebud County
7
Arizona
6
Emery County
6
Matanuska River Valley
6
Missouri
6
Routt County
6
Beaver Creek Watershed (McCreary County)
5
California
5
Converse County
5
Gunnison County
5
Moffat County
5
Pike County
5
Texas
5
China
4
Denver Region
4
Fayette County
4
Germany
4
Haskell County
4
Henry County
4
Huntington
4
Idaho
4
Illinois Basin
4
Jefferson County
4
Las Animas County
4
North Dakota
4
Northwestern States
4
more ...