The Colorado Plateau is a 150,000 square mile region covering parts of Utah, Colorado, Arizona, and New Mexico. It is one of the most beautiful and geologically interesting regions of the world. The Colorado Plateau region covers the northern third of Arizona, the southeastern half of Utah, and a small portion of western Colorado and northeastern New Mexico. The southern border of the Colorado Plateau begins at the White Mountains, where it curves northwestward along the Mongollon Rim and north toward the Grand Canyon in Arizona. In Utah, the northwestern boundary follows the Wasatch Range northward to the Uinta Mountains, where it turns east to Colorado. In Colorado, the northeastern boundary is the western slope of the Rocky Mountains. The southeastern boundary follows the Rio Grande into New Mexico.