Colorado Plateau, upland region, southwestern United States, situated in northern Arizona, southern Utah, southwestern Colorado, and northwestern New Mexico. Also called the Colorado Plateaus, it includes spectacular canyons, high plateaus, and mountains. Generally horizontal and often brilliantly colored strata underlie much of the region. Some of the most notable natural spots of the Colorado Plateau are included in Arches, Bryce Canyon, Canyonlands, Capitol Reef, Grand Canyon, Mesa Verde, and Petrified Forest national parks.