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15 U.S. cities for outdoor enthusiasts

Boulder, Colorado

Photo: Ariel Matzuk/Flickr

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Boulder, Colo.

Hosting more than 100 miles of bike paths and situated less than an hour away from Longs Peak and the Indian Peaks Wilderness, Boulder is a mecca for people who love the outdoors. In fact, the city is surrounded by more than 36,000 acres of recreational open space, conservation easements and nature preserves.

Aside from biking and other outdoor activities, rock climbing is also popular here. Nearby Eldorado Canyon is one of the world's best places for the sport.