Region
United States
22
Colorado
7
England
3
Great Plains
3
Illinois
3
California
2
Chesapeake and Ohio Canal National Historical Park
2
Durango
2
Durango (Colo.)
2
Europe
2
Great Britain
2
India
2
Maryland
2
Sandwich
2
Sandwich (Ill.)
2
Southern States
2
Weld County
2
West (U.S.)
2
Adams County
1
Adams County (Colo.)
1
Brazil
1
Cahokia Mounds State Historic Park
1
Calixtlahuaca
1
Calixtlahuaca (Mexico)
1
Concord (Mass.)
1
Concord Region
1
France
1
High Plains (U.S.)
1
Interstate 70
1
Ireland
1
Korea (South)
1
Massachusetts
1
Mexico
1
Mississippi River Valley
1
Missouri
1
New Jersey
1
North Carolina
1
Ogallala Aquifer
1
Russia
1
Saint Louis County
1
Saint Louis County (Mo.)
1
Santa Clara Valley (Santa Clara County)
1
Santa Clara Valley (Santa Clara County, Calif.)
1
South Dakota
1
Southwestern States
1
Spain
1
Tennessee
1
Texas
1
Tropics
1
Ulysses S. Grant National Historic Site (Mo.)
1
more ...