Region
California
18
Arizona
5
Utah
5
Alaska
4
Delmarva Peninsula
4
Idaho
4
Islands of the Pacific
4
Montana
4
New Mexico
4
United States
4
Coast Ranges
3
Colorado
3
Sierra Nevada (Calif. and Nev.)
3
Antarctica
2
Coast Range
2
Granite Mountains
2
High Plains (U.S.)
2
Hopi Indian Reservation
2
Mid-Atlantic Bight
2
Midway Islands
2
Mojave Desert
2
Navajo Indian Reservation
2
North Carolina
2
North Dakota
2
Oceania
2
Sacramento Valley
2
San Joaquin River Watershed
2
San Joaquin Valley
2
Sangre de Cristo Mountains (Colo. and N.M.)
2
Santa Rita Mountains
2
Victoria Land
2
Washington (State)
2
West (U.S.)
2
Wet Mountain Valley
2
Wyoming
2
Ajo Region
1
Arctic regions
1
Blue Mountains (Or. and Wash.)
1
Blue Mountains Region (Or. and Wash.)
1
Bonneville, Lake
1
Cache County
1
Cache Valley (Utah and Idaho)
1
Chelan County
1
Churchill County
1
Colorado Plateau
1
Death Valley Region (Calif. and Nev.)
1
Delaware
1
Devils Postpile National Monument (Calif.)
1
Devils Postpile National Monument Region
1
East (U.S.)
1
more ...