Region
United States
874
West (U.S.)
74
New Mexico
72
Canada
38
Wyoming
38
North America
34
Colorado
33
Utah
32
Europe
26
Arizona
22
Earth (Planet)
22
Mexico
22
China
20
Soviet Union
20
Texas
19
Australia
18
Southern States
17
Rocky Mountains
16
Latin America
15
Montana
15
Southwestern States
15
Rocky Mountains Region
14
Africa
13
Southwest, New
13
Japan
12
Middle East
12
California
11
Developing countries
11
America
10
Nevada
10
Asia
9
Antarctica
8
New England
8
Galveston Bay
7
Great Britain
7
Idaho
7
San Juan Basin (N.M. and Colo.)
7
British Columbia
6
Caribbean Area
6
Central America
6
Colorado Plateau
6
Colorado River Watershed (Colo.-Mexico)
6
Middle West
6
Pacific Area
6
Powder River Basin (Wyo. and Mont.)
6
Southeast Asia
6
Tropics
6
Arctic regions
5
Asia, Eastern
5
East (U.S.)
5
more ...