1. Arches National Park
2. Bryce Canyon National Park
3. Crater Lake National Park
4. Death Valley National Park
5. Denali National Park
6.
7. Grand Canyon National Park
8. Hawaii Volcanoes National Park
9. Kenai Fjords National Park
10. Mount Rainier National Park
11. Redwood National and State Parks
12. Wrangell-St. Elias National Park
13. Yellowstone National Park
14. Yosemite National Park
15. Shenandoah National Park
Check out the whole series of photos at Wired.