Grand Canyon poster 1938 Adult Apron
It is largely contained within the Grand Canyon National Park, one of the first national parks in the United States. President Theodore Roosevelt was a major proponent of preservation of the Grand Canyon area, and visited it on numerous occasions to hunt and enjoy the scenery. The Grand Canyon is 277 miles (446 km) long, ranges in width from 4 to 18 miles (6.4 to 29 km) and attains a depth of over a mile (1.83 km) (6000 feet). Nearly two billion years of the Earth's geological history have been exposed as the Colorado River and its tributaries cut their channels through layer after layer of rock while the Colorado Plateau was uplifted. While the specific geologic processes and timing that formed the Grand Canyon are the subject of debate by geologists, recent evidence suggests the Colorado River established its course through the canyon at least 17 million years ago. Since that time, the Colorado River continued to erode and form the canyon to the point we see it as today. Before European immigration, the area was inhabited by Native Americans who built settlements within the canyon and its many caves. The Pueblo people considered the Grand Canyon ("Ongtupqa" in Hopi language) a holy site and made pilgrimages to it. The first European known to have viewed the Grand Canyon was García López de Cárdenas from Spain, who arrived in 1540. 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) of unincorporated area in Coconino County and Mohave County. Most visitors to the park come to the South Rim, arriving on Arizona State Route 64. The Highway enters the park through the South Entrance, near Tusayan, Arizona, and heads eastward, leaving the park through the East Entrance. All park accommodations are operated by the Xanterra corporation. Park headquarters are at Grand Canyon Village, a short distance from the South Entrance, being also the center of the most popular viewpoints. Some thirty miles of the South Rim are accessible by road. A much smaller venue for tourists is found on the North Rim, accessed by Arizona State Route 67. There is no road connection between the two within Arizona except via the Navajo Bridge, near Page, Arizona, entailing a five-hour drive. Otherwise, the two rims of the Canyon are connected via Las Vegas, Nevada, and the Hoover Dam. The rest of the Grand Canyon is extremely rugged and remote, although many places are accessible by pack trail and backcountry roads. 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, including its extensive system of tributary canyons, is valued for the combination of large size, depth, and the exposed layering of colorful rocks dating back to Precambrian times. It was created through the incision of the Colorado River and its tributaries after the Colorado Plateau was uplifted and the Colorado River system developed along its present path.