Peter McBride

Two journalists traverse the Grand Canyon by foot, hoping this 750-mile walk will help them better understand one of America's most revered landscapes and the threats poised to alter it forever.

For six million years, the Colorado River ran to the sea. Follow a 1500-mile quest to see why it stopped. Supporting 40 million people across seven states and two countries, learn why the Colorado River is the "most loved and litigated" river in the world.