Grand Canyon National Park is one of the United States' oldest national parks and is located in Arizona. Within the park lies the Grand Canyon, a gorge of the Colorado River, considered to be one of the major natural wonders of the world. The park covers 1,902 mi² (4927 km²).
The area around the Grand Canyon became a national monument on January 11, 1908 and was designated national park on February 26, 1919. The creation of the park was an early success of the environmental conservation movement; its National Park status may have helped thwart proposals to dam the Colorado River within its boundaries. (Lack of this fame may have enabled Glen Canyon Dam to be built upriver, flooding Glen Canyon and creating Lake Powell.) UNESCO has declared it as a World Heritage Site.
The Grand Canyon itself—really an extensive system of tributary canyons— is neither the largest or deepest canyon in the world, but is valued for the combination of large size, depth, and the exposed layering of colourful rocks dating back to Precambrian times. It was created mostly by regional tectonic uplift, but also by erosion from the Colorado River and its tributaries.