One hundred five miles (169 km) of the 217-mile-long (349 km) Grand Canyon make up the Grand Canyon National Park in northwestern Arizona. The canyon, carved by the Colorado River, took more than a billion years to form. It is more than 1 mile deep in places and from four to 18 miles (six to 29 km) wide.

Garcia Lopez de Cardenas, a Spanish explorer, discovered the canyon in 1540. Systematic exploration of the region, however, did not begin until about 1850. John Wesley Powell in 1869 was the first to travel through the canyon by boat. The national park was created in 1919, and has an area of 673,575 acres.