The spiky, soaring cacti that give Saguaro National Park its name aren’t endangered—yet.
But the largest cactus in the United States, which thrives here in the Santa Cruz Valley around Tucson, Arizona, is threatened on many fronts: by invasive species, the state’s building boom, and climate change-fueled wildfires. Thousands of saguaro (pronounced suh-WAA-row) were lost during the record-setting 2020 fire season, which was caused by drought and fueled by invasive, highly flammable South African buffelgrass.
Still, desert plants are hardy, and Arizonans are enamored of the prickly cacti that produces their state flower. They’re volunteering in droves to harvest buffelgrass from Saguaro National Park and other nearby sites.
Symbols of the Southwest, saguaro can grow as tall as 50 feet and often sprout “arms” that appear to be outstretched in hugs. Oak, pine, mesquite, and another two dozen cacti species also thrive alongside them in the national park in the heart of the Sonoran Desert about 60 miles north of the Mexican border.
The park bristles with nearly two million of its namesake cacti in a landscape of volcanic rock backdropped by the chocolate-colored Tucson and Rincon Mountains. The park also holds hundreds of prehistoric petroglyphs created by the Indigenous people who inhabited the region between 550 and 1,550 years ago.
Cacti and cool views
Saguaro National Park is split by Tucson, one of the oldest and longest occupied cities in the U.S. Some sites in the park span more than 8,000 years of occupation. In 2100 B.C., the Sonoran Desert People settled below what is today the western section of the park, called the Tucson Mountain District (TMD), which drains into the intermittent Santa Cruz River. These ancient farmers built the earliest canal irrigation system in the contiguous U.S. Later descendants are also called Hohokam, from huhugam, the modern-day Tohono O’odham’s (“desert people”) word for “ancestors.”
Thirty miles away, the cooler Rincon Mountain District (RMD) is known for its “sky island” plateau with more ruin sites, now mostly inhabited by seldom-seen coati, black bears, and cougars. Sky islands are isolated pockets of habitat that support plant and animal species normally seen at higher latitudes. These mountaintop environments are critical as temperatures are expected to rise. Despite urban encroachments, Saguaro remains an intact desert of extended drought and wind, booming with fierce thunderstorms.
It’s most comfortable to visit Saguaro from October through April, since summer temperatures in the park routinely blaze over 100°F (38°C). Winter temperatures often hit 70°F (21°C) and sometimes drop slightly below freezing at night.
Hikers can explore 165 miles of trails, including the one-mile Freeman Homestead Trail through a grove of saguaro and the 6.4-mile Garwood Dam and Wildhouse Tank Trail with its challenging switchbacks and Santa Catalina Mountain vistas. Biking and horseback-riding are allowed on a few paths, too.
Backcountry camping is permitted at a few sites around the park by reservation only. The National Park Service recommends carrying ample water and being wary of the weather, which can change very quickly.
Indigenous farming and art
During much wetter times, 10,000 years ago in southern Arizona, the first Sonoran Desert People were hunter-gatherers. As large mammals began to diminish, these hunters turned to irrigated farming. Fossilized corn—dated at 2100 B.C .—has been found below the TMD boundary at Las Capas.
Sometime before 1200 B.C.—more than a millennium before the celebrated Hohokam canal builders arrived in Phoenix, 100 miles north—the Sonoran Desert People began to channel the Santa Cruz River into at least 10 canals. The Tucson Las Capas canals watered an orderly system of 250-square-foot fields where ancient dwellers harvested 100 acres of corn and amaranth, and ate the rabbits they found pilfering their crops. Up in the mountains of the park, they hunted deer and bighorn sheep. The village supported up to 150 people, but a flood in 800 B.C. silted over their canal system and pit houses.
As the climate grew hotter and drier, the Sonoran Desert irrigation techniques for beans, squash, cotton, and tobacco spread throughout Arizona. By the year A.D. 300 in the Tucson area, the local inhabitants began painting distinctive red on sand-colored pots. As the ancient Sonoran Desert villages expanded from A.D. 600 to 900, the people there imported food and goods from neighboring tribes, on a trade route that stretched from Mexico to Casa Grande Ruins National Monument in southern Arizona, to northern Arizona and California.
The Sonoran Desert People also drew or pecked art on the darker patina of rocks throughout the park. Abstract spirals, squiggly lines, astrological objects, animals, humans, and other indecipherable drawings may have denoted boundaries or solstice-related calendar dates. For the best viewing, head to the Signal Hill picnic area in the TMD District where maze-like swirls and other designs can be seen via a short nature trail.
In the RMD section of the park, archaeologists have excavated pit houses along with buried human remains, pots, and tools. Eventually the pit-frame homes with poles evolved into aboveground, adobe structures with roofs and solid, rectangular walls. These harbingers of modern Santa Fe-style homes were grouped into compounds surrounding public plazas.
By the early 1400s, the ancient Sonoran Desert People all but vanished along with the ancestral Puebloans (formerly called Anasazi) in other southwestern parks. Whether through disease, drought, or salinization of their crops, the farming culture crashed. Sonoran Desert People’s pottery shards and stone tools can still be found among the more than 500 archaeological sites in the park, washed up in Saguaro’s rocky, volcanic dirt, under a mesquite tree, or alongside stone art.
A version of this article originally appeared in the National Geographic Atlas of the National Parks, which takes readers on an epic journey through the extraordinary and unique features that distinguish these wilderness areas.
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