Region
Colorado
47
Wyoming
45
Montana
33
Utah
29
New Mexico
23
Texas
21
California
16
San Juan Basin (N.M. and Colo.)
14
Alaska
13
Puerto Rico
13
United States
12
Georgia
9
Arizona
8
Kansas
8
North Dakota
8
Bighorn Basin (Mont. and Wyo.)
7
Black Hills (S.D. and Wyo.)
7
South Carolina
7
Alabama
6
Frontier Formation
6
Mesaverde Group
6
New Jersey
6
North America
6
Piceance Creek Basin
6
South Dakota
6
West (U.S.)
6
Grand County
5
Idaho
5
New York (State)
5
Pierre Shale
5
Uinta Basin (Utah and Colo.)
5
Atlantic Coast (U.S.)
4
Beaverhead County
4
Delaware
4
Great Plains
4
Green River Watershed (Wyo.-Utah)
4
Park County
4
Wind River Basin
4
Carbon County
3
Fremont County
3
Front Range (Colo. and Wyo.)
3
Gulf Coast (U.S.)
3
Madison County
3
Madison Range
3
Maryland
3
Massachusetts
3
Mexico
3
Mississippi
3
Oregon
3
Pacific Coast
3
more ...