Region
Wyoming
13
Colorado
9
Montana
8
New Mexico
6
Appalachian Basin
5
Utah
5
Sandoval County
3
Torrance County
3
Valencia County
3
Alaska
2
Arizona
2
Bernalillo County
2
Kansas
2
Oklahoma
2
San Miguel County
2
Santa Fe County
2
South Dakota
2
Wind River Basin (Wyo.)
2
Alaska, Gulf of
1
Bighorn Basin (Mont. and Wyo.)
1
Colfax County
1
Dolores County
1
Douglas Creek area
1
East (U.S.)
1
Fremont County
1
Front Range (Colo. and Wyo.)
1
Grand Banks of Newfoundland
1
Great Plains
1
Green River Formation
1
Illinois Basin
1
Mexico, Gulf of
1
Michigan Basin (Mich. and Ont.)
1
Missouri
1
Montezuma County
1
Nacimiento Mountains
1
North Dakota
1
Pennsylvania
1
Philip Smith Mountains Region
1
Piceance Creek Region
1
Rio Arriba County
1
Rocky Mountains
1
San Juan Basin (N.M. and Colo.)
1
Socorro County
1
Teton County
1
Texas
1
Uinta Formation (Utah)
1
Williston Basin
1
Wilson County
1
Wind River Basin
1