Rocky Mountain National Park

Enos Mills made his living guiding tourists up Longs Peak, but he spent more than a decade lobbying Congress for something he would never be paid for: a national park to protect the Colorado high country he had explored on foot and skis since his teens. Mills modeled his campaign directly on John Muir's fight for Yosemite, writing hundreds of magazine articles and giving lectures across the country to build support most Coloradans, focused on mining and ranching, had not asked for. Congress and President Woodrow Wilson established Rocky Mountain National Park in 1915, protecting more than 400 peaks, including several above 14,000 feet, along the Continental Divide less than 70 miles from Denver.

Ute and Arapaho people had hunted and camped in the high meadows for generations before Euro-American miners and ranchers arrived in the 1860s and 1870s, drawn first by gold and then by the dude-ranch tourism that eventually made Estes Park, the gateway town, more valuable as scenery than as farmland. The road that now carries most visitors across the park, Trail Ridge Road, opened in 1932 and climbs to more than 12,000 feet, making it one of the highest continuous paved roads in North America, a route the National Park Service closes every winter under snow that can bury it 20 feet deep.

More than four million people visit Rocky Mountain National Park each year, most concentrated along Trail Ridge Road and the trails near Bear Lake, while the park's vast alpine tundra above the treeline — roughly a third of its total area — sees far less traffic and hosts elk, bighorn sheep, and some of the coldest, windiest terrain protected anywhere in the lower 48 states.