Rocky Mountain National Park

In the years to come, the air over Rocky Mountain National Park in Colorado is expected to be cleaner thanks to a negotiated settlement that will reduce emissions from power plants in the western half of the state.

Fall is weeks away, yet it's not too early to start planning for your fall or winter excursion. Traveler's Essential Park Guide, Fall 2016, takes a closeup look at Everglades and Shenandoah national parks, and looks farther afield to Costa Rica and Manuel Antonio National Park where you'll find sloths and toucans.

In a word, you could say the National Park System is "busy" this summer. From Acadia National Park in Maine to North Cascades National Park in Washington State, visitation to the parks is high. But that doesn't mean you'll encounter crowds everywhere you go.

Running more than 160 pages, the National Park Service Management Policies provides park managers with quick reference to how they are to manage their units, what uses are appropriate, and how to usher visitors out of the park when Congress fails to fund the National Park Service. But the Management Policies, which last were updated in 2006, also leave much to interpretation and exception.