Grand Canyon

Grand Canyon, spectacular gorge cut by the Colorado River in northwest Arizona. It is more than 200 mi (320 km) long, 4–18 mi (6–29 km) wide, up to 1 mi (1.6 km) deep, and flanked by a plateau 5,000–9,000 ft (1,524–2,743 m) above sea level. The main canyon contains many smaller canyons, peaks, and mesas, and is walled by colorful layers of rock dating back more than 2 million years. Grand Canyon National Park attracts about 2 million visitors each year.