Grand Canyon National Park

Carved by the Colorado River over 5 to 6 million years, the Grand Canyon stretches 277 miles long, up to 18 miles wide, and reaches 1 mile deep in Arizona. Established in 1919, it draws over 6 million visitors annually, which is 30% more than Yellowstone, and exposes nearly 2 billion years of Earth's geological history in its layered rock walls.