Pima County, Arizona
Arizona's second most populous county, home to Tucson, the University of Arizona, Saguaro National Park's towering cactus forests, and world-class astronomical observatories.
Pima County is one of Arizona's original four counties, established on November 8, 1864, when the Arizona Territory was created. Named after the Pima people — the Akimel O'odham, or "River People" — who have inhabited the Sonoran Desert for centuries, the county encompasses 9,186 square miles of some of the most spectacular desert scenery in North America. Tucson, the county seat, is Arizona's second-largest city and one of the oldest continuously inhabited places in the United States, with Native American settlements dating back thousands of years and Spanish colonial missions established in the late 1600s.
Pima County's landscape is defined by the iconic Sonoran Desert, where giant saguaro cacti — the symbol of the American Southwest — stand sentinel across bajadas, canyon mouths, and mountain slopes. Five distinct mountain ranges rise from the desert floor within the county: the Rincon Mountains, Santa Catalina Mountains, Tucson Mountains, Tortolita Mountains, and the Santa Rita Mountains. This sky island geography creates extraordinary biological diversity, with the county home to more bird species than almost anywhere else in North America. The University of Arizona, founded in 1885, anchors Tucson as a center of research, culture, and economic activity, while Davis-Monthan Air Force Base and Raytheon maintain a significant defense industry presence.
County Information
Demographics & Economy
Photos
Major Attractions
Saguaro National Park
Saguaro National Park is split into two districts that flank the city of Tucson, both protecting the dense forests of giant saguaro cactus that define the Sonoran Desert. The Rincon Mountain District (east) encompasses a wilderness of desert and forested mountain slopes, while the Tucson Mountain District (west) features some of the densest saguaro populations anywhere. Scenic drives, hiking trails of all difficulties, and cycling routes thread through both districts. Visitors can observe not only saguaros but also a wealth of desert wildlife including javelinas, Gila woodpeckers, coyotes, and Gila monsters.
Location: Both sides of Tucson
Features: Giant saguaro forests, hiking and biking trails, wildlife viewing, visitor centers, scenic drives
Kitt Peak National Observatory
Perched atop a 6,880-foot mountain in the Quinlan Mountains southwest of Tucson, Kitt Peak National Observatory is one of the world's premier optical astronomy facilities. The complex hosts 22 optical and two radio telescopes operated by multiple research institutions. Daytime tours allow visitors to learn about astronomical research and see the telescope facilities up close. The nighttime observing programs offer one of the most accessible opportunities for the public to view deep-sky objects through professional-grade instruments, far from city light pollution.
Location: 55 miles southwest of Tucson on the Tohono O'odham Nation
Features: Multiple telescope facilities, daytime tours, nighttime observing programs, visitor center, gift shop
Colossal Cave Mountain Park
One of the largest dry caves in the world, Colossal Cave has been a commercial attraction since 1922. The cave's dry conditions have preserved remarkable formations and historical artifacts, including evidence that the cave served as a hideout for outlaws in the Old West era. Guided tours wind through the illuminated caverns, revealing stalactites, stalagmites, and flowstone deposits. The surrounding mountain park features additional attractions including a roping arena, petting farm, trail rides on horseback, and a restored 1930s ranch.
Location: East of Tucson in the Rincon Mountains
Features: Guided cave tours, horseback riding, roping arena, petting farm, historic buildings
Biosphere 2
Located in the Santa Catalina foothills north of Tucson, Biosphere 2 is a unique large-scale science research facility and one of the most unusual structures in the world. The glass and space-frame structure, covering 3.14 acres, contains several enclosed biomes including a tropical rainforest, an ocean with a coral reef, mangrove wetlands, a savanna, a fog desert, and an agricultural area. Originally built for a sealed habitat experiment in the early 1990s, it is now operated by the University of Arizona as a research and education center. Public tours are available daily.
Location: Oracle, north of Tucson
Features: Guided tours, multiple biomes, active science research, educational exhibits, gift shop
Tumacacori National Historical Park
Tumacacori National Historical Park preserves three Spanish colonial missions in the Santa Cruz River valley south of Tucson. The most prominent, Mission San Jose de Tumacacori, was established by Jesuit priests in 1691 as one of the earliest European settlements in present-day Arizona. The adobe and masonry church that still stands today was begun around 1800 by Franciscan missionaries. The park offers a museum, a working pottery kiln, and ranger-led programs exploring the complex history of Spanish colonization, Jesuit and Franciscan missionaries, and the O'odham and Yaqui peoples of the region.
Location: 45 miles south of Tucson along the Santa Cruz River
Features: Historic mission ruins, museum, pottery demonstrations, ranger programs, picnic area
Frequently Asked Questions
Pima County is known for a wide range of distinctive features:
- Tucson, Arizona's second-largest city and one of the oldest continuously inhabited places in the United States
- Saguaro National Park, protecting iconic giant saguaro cactus forests on both sides of Tucson
- The University of Arizona, a major research university and economic anchor
- Exceptional birding, with over 500 species recorded in the region including many rare Mexican species
- Kitt Peak National Observatory, one of the world's premier astronomical facilities
- Davis-Monthan Air Force Base, home to the world's largest aircraft boneyard (AMARG)
- Biosphere 2, a unique large-scale ecological research facility
- Rich Spanish colonial history, including Mission San Xavier del Bac (the "White Dove of the Desert")
- A vibrant arts and culture scene centered in Tucson
- The Santa Catalina "sky island" mountains rising nearly 9,000 feet above the desert
Pima County is easily accessible via multiple transportation routes:
- By Air: Tucson International Airport (TUS) offers direct flights to major hubs including Phoenix, Dallas, Denver, Los Angeles, Chicago, and Seattle, among others.
- By Car: Interstate 10 runs through central Tucson, connecting the county to Phoenix (about 1.5 hours north) and to El Paso, Texas to the east. Interstate 19 runs south from Tucson to Nogales on the Mexican border. US Route 89 provides access from the Flagstaff area via Oracle.
- By Train: Amtrak's Sunset Limited and Texas Eagle routes stop in Tucson, connecting to Los Angeles, New Orleans, and cities in between.
- By Bus: Greyhound and FlixBus offer intercity service to Tucson. Sun Tran provides local public transit throughout the Tucson metropolitan area, supplemented by the Sun Link modern streetcar in downtown Tucson.
Pima County has distinct seasons that suit different types of visitors:
- Spring (March-May): Widely considered the best time, with pleasant temperatures (70s-80s°F), potential for spring wildflower blooms, and excellent hiking conditions. Saguaro cacti bloom with white flowers in May.
- Summer (June-September): The monsoon season arrives in late June or early July, bringing dramatic afternoon thunderstorms and lush green desert conditions. Temperatures in Tucson regularly exceed 100°F, but the mountains provide cooler refuges. Bird diversity peaks during this period.
- Fall (October-November): Another excellent season with comfortable temperatures, clear skies, and excellent hiking. The hummingbird migration brings hundreds of birds to feeders in the mountain canyons.
- Winter (December-February): Mild days (60s-70s°F) with cool nights. Snow occasionally falls on the higher mountain ranges and sometimes on Tucson itself. This is the dry season, and some desert plants are dormant, but the overall landscape remains beautiful.
Tucson was designated a UNESCO City of Gastronomy in 2015, the first city in the United States to receive this designation. The recognition reflects the city's 4,000-year history of agriculture and unique culinary traditions:
- Sonoran-style Mexican food, distinct from other regional Mexican cuisines, featuring specific dishes like the Sonoran hot dog (bacon-wrapped hot dog in a bolillo bun with pinto beans, tomato, onion, mustard, mayonnaise, and jalapeno salsa)
- Use of native Sonoran Desert foods including prickly pear, cholla buds, mesquite flour, tepary beans, and saguaro fruit syrup
- A thriving farm-to-table movement connected to local agriculture in the Santa Cruz Valley
- Historic food traditions of the Tohono O'odham people
- A diverse restaurant scene ranging from traditional Mexican family restaurants to cutting-edge chef-driven establishments
- Farmers markets and food festivals throughout the year celebrating local food traditions
Major Communities
Tucson
County seat and Arizona's second-largest city, population ~542,000
Marana
Population ~50,000, fast-growing community northwest of Tucson
Oro Valley
Population ~44,000, affluent suburb north of Tucson
Sahuarita
Population ~32,000, growing community south of Tucson
South Tucson
Population ~5,600, independent city within Tucson metro known for Mexican food
Green Valley
Population ~21,000, major retirement community south of Tucson