Region
- United States 90 results
- Developing countries 12 results
- Colorado 10 results
- Africa 8 results
- Asia 6 results
- China 6 results
- Cold regions 6 results
- Europe 6 results
- North America 6 results
- Arizona 2 results
- California 2 results
- Canada 2 results
- Developed countries 2 results
- European Union countries 2 results
- Former Soviet republics 2 results
- Glen Canyon Dam (Ariz.) 2 results
- Glen Canyon Dam Region 2 results
- Hoover Dam (Ariz. and Nev.) 2 results
- India 2 results
- Iran 2 results
- Middle East 2 results
- Nevada 2 results
- New Jersey 2 results
- New York (State) 2 results
- Outer space 2 results
- Panama Canal (Panama) 2 results
- Rome 2 results
- Russia (Federation) 2 results
- San Francisco 2 results
- San Francisco Bay Area 2 results
- Yucca Mountain 2 results