Pima County, located in southern Arizona, encompasses approximately 9,189 square miles and is home to over 1 million residents, with Tucson as its vibrant county seat and largest city. Named after the Akimel O’odham (Pima) people, the region has been shaped by millennia of indigenous habitation, colonial explorations, territorial conflicts, and modern urban expansion. This report chronicles the county’s history from prehistoric times to the present, highlighting key events, cultural influences, and significant points of interest that embody its rich heritage.
Prehistoric and Indigenous Foundations (12,000 BCE – 1692 CE)
Human presence in Pima County dates back over 12,000 years to Paleo-Indians who hunted mammoths and gathered along the Santa Cruz River. By 2100 BCE, Archaic peoples developed early irrigation canals—the first in North America—for farming corn, beans, and squash. From 600 to 1450 CE, the Hohokam culture flourished, constructing an extensive network of canals, ball courts, and villages, leaving behind red-on-buff pottery and platform mounds. Their descendants, including the Tohono O’odham and Akimel O’odham, continued to inhabit the Sonoran Desert, adapting to its arid environment through sustainable agriculture and trade.
These indigenous legacies are preserved in sites like the Arizona State Museum in Tucson, which houses one of the world’s finest collections of Southwestern Native American artifacts, including Hohokam pottery and textiles, offering insights into pre-Columbian life. The San Xavier Indian Reservation, home to the Tohono O’odham, remains a living cultural hub, where traditional practices and the annual All Indian Rodeo highlight ongoing O’odham heritage.
Spanish Colonial Era (1692 – 1821)
European contact began in 1692 when Jesuit missionary Eusebio Francisco Kino explored the area, founding Mission San Xavier del Bac in 1700—a stunning Baroque-style “White Dove of the Desert” still standing today as the oldest intact European structure in Arizona. Built between 1783 and 1797, the mission served as a center for Tohono O’odham conversion and agriculture, blending Spanish architecture with indigenous labor.
In 1775, Spanish authorities established the Presidio San AgustÃn del Tucson to protect against Apache raids, marking the official founding of Tucson. This walled fort evolved into a multicultural settlement of Spanish soldiers, Mexican settlers, and Native Americans. The Presidio Museum in downtown Tucson recreates this era with artifacts, adobe structures, and exhibits on daily frontier life, including the Second Battle of Tucson in 1782, where Pima and Papago allies repelled Yavapai and O’odham attackers.
Mexican Period and Transition to U.S. Control (1821 – 1863)
Mexico’s independence in 1821 integrated Tucson into the state of Sonora, but isolation persisted amid Apache conflicts. The 1846 Mexican-American War brought the Mormon Battalion to Tucson, who encountered “wild bulls” along the San Pedro River in a humorous skirmish. The pivotal 1853 Gadsden Purchase ceded southern Arizona, including Pima County, to the U.S. for $10 million to facilitate a southern transcontinental railroad.
This era’s tensions are echoed in the De Anza National Historic Trail, a 1,200-mile route through Pima County commemorating Juan Bautista de Anza’s 1775–1776 expeditions, with interpretive sites highlighting Spanish-Mexican overland journeys.
American Territorial and Statehood Era (1863 – 1912)
The Civil War briefly made Tucson the Confederate capital in 1861 under John R. Baylor, but Union forces reclaimed it in 1862 via the California Column. The 1863 Arizona Organic Act created the Arizona Territory, with Pima County organized on November 9, 1864, as one of four original counties, initially vast but later carved into others like Cochise and Santa Cruz. Tucson served as territorial capital from 1867 to 1877, fostering growth with the arrival of the Southern Pacific Railroad in 1880, which brought Chinese immigrants who established laundries, farms, and markets.
The University of Arizona, founded in 1885, became a cornerstone of education and research. Statehood arrived on February 14, 1912, boosting infrastructure. Historical sites like Old Tucson Studios, built in 1939 as a movie set for Westerns like Rio Bravo, capture this cinematic territorial romance, offering gunfight shows and stagecoach rides amid adobe facades.
20th Century Growth and Modern Developments (1912 – Present)
Tucson’s dry climate attracted tuberculosis patients in the early 1900s, earning it the nickname “Sanatorium City,” with facilities like the 1928 Veterans Administration Hospital. World War II spurred Mexican-American activism through groups like the Spanish-American Mothers and Wives Association, while Davis-Monthan Air Force Base (established 1941) solidified military ties.
Postwar suburbanization exploded the population—from 36,818 in 1940 to over 500,000 by 2000—with Pima County reaching 1,043,433 by 2020. The 1960s space race linked the region to aerospace via the Pima Air & Space Museum, showcasing 300+ aircraft, including Cold War relics like the Titan II Missile Site in Green Valley, the only publicly accessible ICBM silo.
Today, Pima County balances urban innovation with conservation through the Sonoran Desert Conservation Plan, protecting biodiversity in areas like Saguaro National Park (established 1933, expanded 1991), where iconic cacti symbolize the desert’s resilience. Challenges include water scarcity and growth pressures, but cultural festivals like La Fiesta de San AgustÃn (Tucson’s birthday since 1775) preserve its multicultural soul.
Pima County National Protected Areas
- Buenos Aires National Wildlife Refuge
- Cabeza Prieta National Wildlife Refuge
- Coronado National Forest
- Ironwood Forest National Monument
- Las Cienegas National Conservation Area
- Organ Pipe Cactus National Monument
- Saguaro National Park