As the National Park Service kicks off a centennial summer expected to draw record crowds, the agency is seriously considering caps on how many people pass through some of the country's most iconic landscapes and historical sites each day.

Park managers have begun looking at whether, when and how best to manage the impact of more people on the parks, their features and the visitors' experience.

Denali and Yellowstone plan to survey visitors about their experiences this summer, hoping the responses will provide insight on what limitations visitors might accept.

Arches and Canyonlands national parks in Utah have been taking public comment on their plans for tighter rules about how many people can be in the park at the same time.