Region
United States
37
Iowa
4
Great Basin
2
Great Plains
2
New Mexico
2
Arizona
1
Atlantic Ocean
1
California
1
Chesapeake Bay (Md. and Va.)
1
Colorado
1
Davidson Seamount
1
Grant-Kohrs Ranch National Historic Site
1
Grant-Kohrs Ranch National Historic Site (Mont.)
1
Great Falls Park
1
Great Falls Park (Va.)
1
Middle West
1
Mississippi River
1
Montana
1
Monterey Bay National Marine Sanctuary
1
Nevada
1
New Zealand
1
North America
1
Oregon
1
Pacific Ocean
1
Sierra Nevada (Calif. and Nev.)
1
Southern States
1
Virginia
1
West (U.S.)
1