Despite its harshness, life thrives in the Sonoran Desert. Cactus trees, paloverdes, desert tortoises, Gila monsters, and roadrunners are among the hundreds of plant and animal species that make their home there. The Sonoran Desert lies in the arid region west of the Rocky Mountains. It covers about 120,000 square miles of land in southern California, Arizona, and Mexico. The Mojave, Yuma, Pima, Chemehuevi, and Papago Indian reservations are located there. Tucson and Phoenix are two of the desert’s largest cities. Much of the area’s rain doesn’t come until the middle of summer, when it falls in sudden downpours. With its thick, straight trunk and sturdy, curved branches, the saguaro cactus is one of the most identifiable plants of the Sonoran Desert. This mammoth cactus can attain a height of 50 feet and weight of eight tons over its 200 years of slow growth. Many desert animals depend on the saguaro for nourishment and shelter, including wood rats, Gila woodpeckers, gilded flickers, elf owls, and sparrow hawks, among others.