Region
- United States 90 results
- Colorado 38 results
- Soviet Union 10 results
- Developing countries 9 results
- Japan 9 results
- China 7 results
- Boulder 6 results
- Denver 6 results
- California 5 results
- Latin America 5 results
- Mexico 5 results
- Korea (South) 4 results
- Africa, Sub-Saharan 3 results
- Chile 3 results
- Europe, Western 3 results
- France 3 results
- Germany 3 results
- Asia 2 results
- Botswana 2 results
- Boulder (Colo.) 2 results
- Brazil 2 results
- Canada 2 results
- Cuba 2 results
- Europe 2 results
- Europe, Eastern 2 results
- Great Britain 2 results
- Iran 2 results
- Israel 2 results
- Middle East 2 results
- New York 2 results
- New York (State) 2 results
- Nicaragua 2 results
- Philippines 2 results
- Russia 2 results
- Taiwan 2 results
- Yellowstone National Park 2 results
- Africa 1 results
- Africa, West 1 results
- Algeria 1 results
- Austria 1 results
- Bahrain 1 results
- Baltimore 1 results
- Boulder County 1 results
- Burma 1 results
- Clark Fork Watershed (Mont. and Idaho) 1 results
- Colorado River (Colo.-Mexico) 1 results
- Columbia River Watershed 1 results
- Costa Rica 1 results
- Denver Metropolitan Area (Colo.) 1 results
- Egypt 1 results more…