Region
- United States 45 results
- Developing countries 6 results
- Colorado 5 results
- Africa 4 results
- Asia 3 results
- China 3 results
- Cold regions 3 results
- Europe 3 results
- North America 3 results
- Arizona 1 results
- California 1 results
- Canada 1 results
- Developed countries 1 results
- European Union countries 1 results
- Former Soviet republics 1 results
- Glen Canyon Dam (Ariz.) 1 results
- Glen Canyon Dam Region 1 results
- Hoover Dam (Ariz. and Nev.) 1 results
- India 1 results
- Iran 1 results
- Middle East 1 results
- Nevada 1 results
- New Jersey 1 results
- New York (State) 1 results
- Outer space 1 results
- Panama Canal (Panama) 1 results
- Rome 1 results
- Russia (Federation) 1 results
- San Francisco 1 results
- San Francisco Bay Area 1 results
- Yucca Mountain 1 results