Located in Arizona, Grand Canyon National Park was founded in 1919. It encompasses 277 miles (446 km) of the Colorado River and adjacent uplands. It s one of the oldest national parks in the United States and is home to the awe-inspiring Grand Canyon, a 1-mile deep gorge carved by the Colorado River. Long considered one of the seven wonders of the world, visitors flock to see this unique combination of geological color and erosional forms.