Region
United States
21,667
Colorado
128
West (U.S.)
113
Washington (D.C.)
95
Canada
82
California
79
Utah
73
Nevada
71
China
67
Oregon
66
Mexico, Gulf of
64
Texas
60
Wyoming
60
New Mexico
57
Missouri River Watershed
54
Outer space
52
Alaska
45
North America
42
Idaho
41
Arizona
40
Colorado River Watershed (Colo.-Mexico)
38
Europe
38
Mexico
37
Soviet Union
37
Ohio
36
Washington (State)
35
Montana
34
Japan
32
Mississippi River Watershed
32
Tennessee
32
Pennsylvania
30
Illinois
29
United States Virgin Islands
29
Virginia
28
Alabama
26
Maryland
26
Yellowstone National Park
25
Germany
24
Louisiana
23
Puerto Rico
23
Atlantic Coast (U.S.)
22
Iraq
21
Southwestern States
21
Florida
20
France
20
Missouri
20
Kansas
19
Kentucky
19
Michigan
19
Middle West
18
more ...