Sonoran Desert
The lush North American desert of the towering saguaro cactus
The Sonoran Desert is the greenest of North America's deserts, a startlingly alive landscape spread across roughly 260,000 square kilometres of southern Arizona, southeastern California, and the Mexican states of Sonora and Baja California. It is defined above all by the saguaro, the giant branching cactus that can stand over twelve metres tall and live two centuries, an icon of the American Southwest. Two distinct rainy seasons, winter and summer, give the Sonoran a biological richness unmatched by any other desert in the region.
That double rainfall, gentle winter storms and violent summer monsoon thunderstorms, supports an extraordinary diversity of life: more than 2,000 plant species, from saguaro and organ pipe cactus to palo verde and ocotillo, and animals including the desert tortoise, Gila monster, javelina, and roadrunner. The terrain ranges from low, hot basins and the searing dunes near the Colorado River delta to cooler, vegetated mountain ranges that rise like islands above the desert floor, each harbouring its own communities of plants and creatures.
The desert has been home to people for thousands of years, including the Tohono Oodham, whose ancestors built sophisticated canal systems, and whose harvest of the saguaro fruit still marks the start of their traditional year. The Hohokam who preceded them engineered hundreds of kilometres of irrigation canals across the Phoenix basin. Today the Sonoran cradles fast-growing cities like Phoenix and Tucson, even as protected lands such as Saguaro National Park preserve the cactus forests that make this desert unlike any other.