(Photo courtesy of Grand Canyon National Park)

Grand Canyon's South Kaibab Trail.

The National Parks Service marks its 100th anniversary today, and Arizona’s ties to the NPS are deep.

That’s in large part due to the Grand Canyon, the emotional reactions it generates, and the thousands of tourists who go there every year.

There’s an even broader relationship and one that isn’t only about hikes and beautiful views.

To dig in deeper and go off the trail a bit, we spoke with Arizona Highways Editor in Chief Robert Stieve and ASU professor David Foster.