Saguaro National Park

Saguaro National Park sits in southeastern Arizona, split into two sections that flank Tucson. The Tucson Mountain District lies about 10 miles west of the city, while the Rincon Mountain District is about 10 miles east. Together, they cover 92,000 acres of Sonoran Desert, protecting its wildlife and plants—most famously, the giant saguaro cactus.

The two districts have very different surfaces. The Tucson Mountain District is covered in volcanic rock, but the Rincon Mountain District’s rocks came from beneath the Tucson Mountains, shifted over 30 million years by crustal stretching. The Rincon Mountains were later uplifted, domed, and eroded, making them much higher and wetter than the Tucson Mountains. As part of the Madrean Sky Islands—a chain between the southern Rockies and Mexico’s Sierra Madre Oriental—the Rincons host a high level of biodiversity, with many species that don’t appear in the Tucson Mountain District.

Long before the park existed, the area was home to the Hohokam, Sobaipuri, Tohono O’odham, and Apache peoples, and was visited by Spanish explorers, missionaries, miners, homesteaders, and ranchers. In 1933, President Herbert Hoover used the Antiquities Act to create Saguaro National Monument in the Rincon Mountains. President John F. Kennedy added the Tucson Mountain District in 1961, renaming the original tract the Rincon Mountain District. Congress combined both districts into a national park in 1994.

Visitors can hike 165 miles of trails or take scenic drives near two visitor centers. Both districts allow bicycling and horseback riding on certain roads and trails. The Rincon Mountain District has limited wilderness camping, but overnight camping is not permitted in the Tucson Mountain District.

The park takes its name from the saguaro, a large cactus native only to the Sonoran Desert. “Rincón” is Spanish for “corner,” describing the shape of the mountain range. “Tucson” comes from Papago-Piman words meaning “dark spring” or “brown spring.” “Tanque” refers to a small artificial pool behind a dam that traps runoff. “Madrean” comes from “Madre” in Sierra Madre, meaning “Mother Mountains.”

The two districts are about 10 miles from downtown Tucson. As of 2016, their combined area was 91,716 acres: the Tucson Mountain District covers about 25,000 acres, and the Rincon Mountain District about 67,000 acres. Roughly 71,000 acres across both districts are designated wilderness. Interstate 10 runs through Tucson. Tucson Mountain Park borders the Tucson Mountain District to the south, with Avra Valley to the west. The Rincon Mountain Wilderness, a separate 37,000-acre protected area in Coronado National Forest, lies east and southeast of the Rincon Mountain District, while Rincon Valley sits south of its western portion.

Elevations in the Tucson Mountain District range from 2,180 feet to 4,687 feet at Wasson Peak. In the Rincon Mountain District, elevations vary from 2,670 feet to 8,666 feet at Mica Mountain. The park lies in the watershed of the north-flowing Santa Cruz River, which is usually dry. Rincon Creek, free-flowing for part of the year, has the largest riparian zone in the park. It feeds into Pantano Wash, which meets Tanque Verde Wash to form the Rillito River, a dry wash tributary of the Santa Cruz. Washes in both districts are typically dry but can flash flood. Smaller riparian areas exist near springs and tinajas in the Rincon Mountain District; the largest spring is at Manning Camp.

The park has a hot semi-arid climate. At the Red Hills Visitor Center (2,553 feet), the plant hardiness zone is 9b, with an average annual extreme minimum of 25.8°F. At the Rincon Mountain Visitor Center (3,091 feet), it’s 9a, with an average annual extreme minimum of 23.4°F. Summer rains are brief and violent, often with lightning, dust storms, and flash floods. In winter, snow falls at the highest elevations in the Rincons, and snowmelt later provides limited water at lower elevations. From 1900 to 2010, the park’s annual mean temperature rose about 4°F.

The park’s oldest rocks, the Pinal Schist, formed about 1.7 billion years ago, before the Basin and Range Province—of which the park is part—even existed.