National parks actually glow in autumn. From the fluttering gold of aspens and larch in the parks along the spine of the Rocky Mountains to the oranges, yellows and reds of the hardwood forests that cover Eastern parks and even on the Southwest’s sandstone, fall is the season of incandescence in the park system. Where do you find these rainbows? Here’s your guide to the "best bets" for fall color in the National Park System.