Grand Canyon National Park, located in northwestern Arizona, is the 15th site in the United States to have been named as a national park. The park's central feature is the Grand Canyon, a gorge of the Colorado River, which is often considered one of the Wonders of the World. The park, which covers 1,217,262 acres of unincorporated area in Coconino and Mohave counties, received more than 4.7 million recreational visitors in 2023. The Grand Canyon was designated a World Heritage Site by UNESCO in 1979. The park celebrated its 100th anniversary on February 26, 2019.

The Colorado Plateau, also known as the Colorado Plateau Province, is a physiographic and desert region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. This province covers an area of 336,700 km2 (130,000 mi2) within western Colorado, northwestern New Mexico, southern and eastern Utah, northern Arizona, and a tiny fraction in the extreme southeast of Nevada. About 90% of the area is drained by the Colorado River and its main tributaries: the Green, San Juan, and Little Colorado. Most of the remainder of the plateau is drained by the Rio Grande and its tributaries.