Arizona is, of course, the Grand Canyon State, and the national park is considered a crown jewel of the system.

But the park, and the canyon itself, are facing challenges.

Writer Kevin Fedarko and photographer and filmmaker Pete McBride will be speaking about some of them tonight at the Mesa Arts Center, as part of the National Geographic Live series. Their presentation is called “Between River and Rim: Hiking the Grand Canyon,” and they did just that — hike the whole thing.

They join The Show's Mark Brodie to talk about their experience and what they learned.