Region
United States
20
Chicago
6
Chicago (Ill.)
6
Illinois
6
Foreign countries
5
California
4
New York
4
New York (N.Y.)
4
New York (State)
4
Pennsylvania
4
Philadelphia
3
Philadelphia (Pa.)
3
Baltimore
2
Baltimore (Md.)
2
Colorado
2
Connecticut
2
Conservation of natural resources
2
Delta County
2
Environmental policy
2
Fremont County
2
Jersey City
2
Jersey City (N.J.)
2
Lander
2
Maryland
2
Milwaukee
2
Milwaukee (Wis.)
2
New Jersey
2
New York County
2
New York County (N.Y.)
2
Paonia
2
Poland
2
Russia
2
Soviet Union
2
West (U.S.)
2
Wisconsin
2
Wyoming
2
Canada
1
Delaware
1
Los Angeles
1
Los Angeles (Calif.)
1
Los Angeles County
1
Los Angeles County (Calif.)
1
New York, NY
1
Pasadena
1
Pasadena (Calif.)
1
Philadelphia County
1
Philadelphia County (Pa.)
1
United States, West
1
West United States
1
Wilmington
1
more ...