Region
California
2
Nevada
2
Yellowstone National Park
2
Alaska, Southcentral
1
Baffin Island
1
Chesapeake and Ohio Canal National Historical Park
1
Manix Lake
1
Manix Lake (Calif.)
1
Nunavut
1
Potomac River Valley
1
Pyramid Lake
1
Pyramid Lake (Nev.)
1
Salt Lake County
1
Searles Valley
1
Sicily, Strait of
1
Utah
1
Yucca Mountain Region
1