The Grand Canyon is a steep-sided canyon carved by the Colorado River in Arizona, United States [1] [2]. It is a globally recognized natural wonder, attracting millions of visitors annually due to its immense size, intricate and colorful landscape, and significant geological exposures [2] [3]. The canyon is approximately 277 miles (446 km) long, up to 18 miles (29 km) wide, and over a mile (6,093 feet or 1,857 meters) deep [2].

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The Grand Canyon's formation is a result of nearly two billion years of Earth's geological history, exposed as the Colorado River and its tributaries cut channels through layers of rock while the Colorado Plateau was uplifted [2]. While some aspects of its incision history are debated, recent studies suggest the Colorado River established its course through the area about 5 to 6 million years ago [2]. However, other research indicates that parts of the canyon could be much older, with some segments potentially forming as far back as 70 million years ago [2]. The current scientific consensus is that the canyon is composed of multiple segments that formed at different times and eventually connected [2]. The major geological exposures range in age from the two-billion-year-old Vishnu Schist at the bottom to the 270-million-year-old Kaibab Limestone on the rim [2]. The uplift of the Colorado Plateau, starting about 65 million years ago, significantly steepened the river's gradient, increasing its ability to cut through rock [2].

For thousands of years, Native American communities have continuously inhabited the Grand Canyon area, building settlements within the canyon and its many caves [2]. The Pueblo people, for instance, considered it a holy site [2]. Today, the Grand Canyon is located on the ancestral homelands of 11 present-day Tribal Communities, including the Hualapai Indian Reservation and the Havasupai Indian Reservation [1] [2]. The first European known to have viewed the Grand Canyon was García López de Cárdenas from Spain in 1540 [2]. It was established as a national monument in 1908 and officially became Grand Canyon National Park in 1919 [2].

The park encompasses 278 miles (447 km) of the Colorado River and adjacent uplands [1]. The Grand Canyon's vast biological diversity is attributed to the presence of five of North America's seven life zones and three of its four desert types, a result of the significant elevation change from the Colorado River to the highest point on the North Rim [2]. This elevation difference also leads to varied weather conditions, with the forested rims receiving winter snowfall and the Inner Gorge experiencing desert-like temperatures [2].

Tourism is a major aspect of the Grand Canyon, with approximately five million visitors annually [2]. The South Rim is the most popular and accessible area, open year-round, offering visitor centers, museums, and various attractions [2] [4] [5]. The North Rim, generally open from mid-May to mid-October, provides a less crowded experience [2] [5]. Grand Canyon West, located on the Hualapai Indian Reservation, is another significant tourist area, known for its glass-bottomed Skywalk, which extends 70 feet over the rim, 4,000 feet above the canyon floor [2] [6]. Activities available include hiking, rafting, helicopter tours, mule rides, and zip-lining [2] [5] [6].