History of Pinal County, Arizona
Introduction to Pinal County
Pinal County, located in central Arizona, has a rich history shaped by Native American cultures, Spanish exploration, and American settlement. Established in 1875, the county grew rapidly due to its fertile farmlands, rich mineral deposits, and its role as a transportation hub. Historically a center for agriculture, mining, and the development of the American West, Pinal County continues to grow with a diverse economy today. Its landscape includes desert plains, mountain ranges, and important historical landmarks, making it a unique and vibrant region in Arizona.
County Facts
- Founded: February 1, 1875
- Population: Approximately 439,128 (2020 Census)
- Area: 5,374 square miles (13,915 km²)
- Area Code: 520
- ZIP Codes: 85118–85193, 85220–85223
- County Seat: Florence
- Major Cities: Casa Grande, Florence, Coolidge, Maricopa, Apache Junction, Eloy
- Famous Landmarks: Casa Grande Ruins National Monument, Superstition Mountains, Picacho Peak State Park, Boyce Thompson Arboretum, Florence Historic District
Early History of Pinal County
Pre-Colonial Era (Pre-1500)
Long before European contact, the region that would become Pinal County was home to several Indigenous cultures, most notably the Hohokam, who lived in the area from around 300 AD to 1450 AD. The Hohokam were known for their extensive and sophisticated irrigation canal systems, which allowed them to farm the arid land of central Arizona. They grew crops such as maize, beans, and squash and constructed large villages throughout the Gila River Valley.
By 1450, the Hohokam culture mysteriously declined, leaving behind a vast system of canals and other artifacts. The Akimel O’odham (Pima) and the Tohono O’odham people, descendants of the Hohokam, continued to live in the region, utilizing the land’s resources.
Spanish Exploration (1500s-1700s)
In the 1500s, Spanish explorers ventured into what is now Arizona as part of their larger quest to expand New Spain and spread Christianity. One of the most notable Spanish explorers, Francisco Vásquez de Coronado, passed through the region in search of the legendary Seven Cities of Gold. However, Spanish colonization of this region remained limited due to its remoteness and the hostile desert environment.
By the late 1600s, Spanish missionaries began attempting to convert local Native American tribes to Christianity. One of the most significant figures during this time was Father Eusebio Francisco Kino, a Jesuit missionary who traveled through the region in the late 1600s and early 1700s. Father Kino’s expeditions laid the groundwork for later Spanish missions and settlements in southern Arizona.
Mexican and American Territorial Periods (1821-1912)
Mexican Independence and Early Settlement (1821–1848)
When Mexico gained independence from Spain in 1821, the region that now includes Pinal County became part of the Mexican state of Sonora. However, Mexican influence in the region was limited, with only a few small settlements and missions. The remote, rugged terrain and lack of infrastructure made large-scale colonization difficult.
After the Mexican-American War (1846–1848), the Treaty of Guadalupe Hidalgo ceded much of the southwestern United States, including Arizona, to the United States. This marked the beginning of American expansion into the region.
Gadsden Purchase and Expansion (1853)
The Gadsden Purchase of 1853 further expanded American territory in southern Arizona, securing the region that would become Pinal County. The purchase was primarily motivated by the need for land to build a southern transcontinental railroad route. In the years following the Gadsden Purchase, American settlers, miners, and military personnel began to move into the area.
The discovery of rich mineral deposits, particularly gold and silver, in the 1850s and 1860s attracted more settlers and prospectors. Mining camps and small settlements, including Florence, were established to support mining operations.
Establishment of Pinal County (1875)
Pinal County was officially established on February 1, 1875, carved out of parts of Pima and Maricopa Counties. The county was named after the Pinal Mountains, located to the southeast. Florence was designated as the county seat due to its strategic location along the Gila River and its role as a key stop for travelers and traders in the region. Florence would later become a center for law and order in the Arizona Territory, as it was home to one of the earliest territorial prisons.
Economic and Cultural Development (Late 1800s-Early 1900s)
Mining and Ranching Boom (1870s-1900s)
The late 19th century saw a boom in mining and ranching in Pinal County. Silver was discovered near the Silver King Mine in the Superstition Mountains in 1875, leading to the establishment of nearby towns like Superior. Mining quickly became a dominant industry, with gold, copper, and silver driving economic growth.
At the same time, ranching became an important part of the county’s economy. Vast areas of land were used for cattle ranching, and the establishment of railroads in the 1880s allowed for the easier transportation of livestock and agricultural products to market.
Casa Grande Ruins National Monument (1892)
One of the most significant historical landmarks in Pinal County is the Casa Grande Ruins, which were designated as a national monument in 1892. The ruins are the remains of an ancient Hohokam structure built around 1350 AD. This impressive four-story structure, likely used for ceremonial or astronomical purposes, has stood for centuries and remains a key cultural and archaeological site in the county.
20th Century Growth and Development
Agriculture and Irrigation (1900s-1940s)
While mining and ranching remained important industries, the early 20th century saw a shift toward agriculture in Pinal County. The construction of the Coolidge Dam on the Gila River in 1928 helped to irrigate large areas of farmland, transforming the arid desert into fertile land. Crops such as cotton, alfalfa, and wheat became major agricultural products, and farming became a cornerstone of the county’s economy.
Towns like Coolidge and Casa Grande grew as agricultural centers, attracting workers and settlers to the region. The creation of the Salt River Project and other irrigation initiatives helped stabilize water resources, ensuring the continued growth of agriculture in Pinal County.
World War II and Post-War Expansion (1940s-1960s)
World War II brought further development to Pinal County, with the establishment of military bases and prisoner-of-war camps. The Casa Grande Army Airfield was one such facility, used for training pilots during the war. After the war, many veterans and their families moved to the region, attracted by the available land and growing opportunities in agriculture and industry.
The post-war era also saw the expansion of infrastructure, including roads and schools, as the county’s population began to increase. The Interstate Highway System, established in the 1950s, further connected Pinal County to major cities like Phoenix and Tucson, facilitating trade and travel.
Modern Development and Economic Diversification (1970s-Present)
Growth of Suburban Communities (1970s-2000s)
From the 1970s onward, Pinal County experienced rapid population growth due to its proximity to the expanding metropolitan areas of Phoenix and Tucson. Suburban communities such as Apache Junction and Maricopa began to grow rapidly, providing affordable housing for people who worked in the larger cities but preferred to live in more rural or suburban settings.
This population boom led to increased demand for services, schools, and infrastructure, transforming the county from a largely rural, agricultural region into a rapidly urbanizing area. The construction of new housing developments, shopping centers, and businesses brought further economic growth.
Economic Diversification and Industry (2000s-Present)
In recent decades, Pinal County has diversified its economy beyond agriculture and mining. The county has seen growth in manufacturing, renewable energy, and technology industries. Companies like Lucid Motors, an electric vehicle manufacturer, established operations in the county, providing new jobs and stimulating economic growth.
Tourism also continues to play an important role in the local economy, with visitors drawn to the county’s natural beauty, historical sites, and outdoor recreational opportunities, including hiking in the Superstition Mountains and visiting the Boyce Thompson Arboretum.
The county’s population continues to grow, making it one of the fastest-growing areas in Arizona. This rapid growth presents both opportunities and challenges, as the county works to balance development with the preservation of its cultural and natural heritage.
Key Landmarks and Attractions in Pinal County
Casa Grande Ruins National Monument
The Casa Grande Ruins National Monument is one of the most significant historical and archaeological sites in the American Southwest. Built by the Hohokam people around 1350 AD, the ruins include a massive four-story structure that likely served as a ceremonial center. Today, the site is protected as a national monument and draws visitors interested in learning about ancient Native American cultures.
Superstition Mountains
The Superstition Mountains are one of Arizona’s most iconic natural landmarks. Known for their rugged beauty and rich history, the mountains are associated with tales of the Lost Dutchman’s Gold Mine, a legendary gold mine said to be hidden somewhere in the range. The Superstitions are a popular destination for hikers, campers, and adventure-seekers.
Picacho Peak State Park
Picacho Peak State Park is a prominent landmark along Interstate 10, known for its dramatic peak and stunning desert scenery. The park is famous for its hiking trails, particularly the challenging climb to the top of Picacho Peak, and for being the site of the westernmost battle of the American Civil War.
Boyce Thompson Arboretum
Located near Superior, the Boyce Thompson Arboretum is Arizona’s oldest and largest botanical garden. Established in 1924, the arboretum is home to thousands of species of plants from deserts around the world, and it serves as an important center for plant conservation and education.
