Region
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Former Soviet republics
2
Frederick
2
Galveston
2
Gold King Mine (San Juan County, Colo.)
2
Gulf Coast (U.S.)
2
Indiana
2
Italy
2
Jacksonville
2
Kingston
2
Los Angeles
2
Makassar
2
Mali
2
Mauritius
2
Monroe County (Fla.)
2
Nevada
2
New Mexico
2
Northern Ireland
2
Northern Mariana Islands
2
Northwest, Pacific
2
Nova Scotia
2
Oaxaca Valley
2
Oklahoma
2
Outer space
2
Peru
2
Prince George's County
2
San Antonio
2
San Antonio (Tex.)
2
San Juan County
2
Singapore
2
South Dakota
2
Tunisia
2
United States Virgin Islands
2
Utah
2
Virginia
2
Africa, North
1
Arctic National Wildlife Refuge (Alaska)
1
Argentina
1
Ashland (Va.)
1
Austria
1
Baltic Sea Region
1
Baltic States
1
Beaver County
1
Belize
1
Black Hills National Forest (S.D. and Wyo.)
1
Botswana
1
Cali (Colombia)
1
California, Northern
1
California, Southern
1
Cameroon
1
Canada, Northern
1
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