The area's original inhabitants were Native Americans who found that the lush area along the Sonoita and Harshaw Creeks provided ideal living conditions with plentiful hunting and fishing opportunities. In 1539, Spanish explorer Fray Marcos de Niza entered the area near present-day Lochiel on the Mexican border. A century and a half later, the Jesuit priest Padre Eusebio Francisco Kino traveled through the region, establishing missions and mapping the territory.
Spanish mission records indicate that in 1698 Father Eusebio Francisco Kino encouraged his group to leave the San Pedro River and make their way up to Sonoita Creek. There they encountered clusters of indigenous people living along Sonoita Creek in Patagonia, and in 1701, Father Kino designated Sonoita as one of his visitas. The area then became part of the Mission at Guevavi.
The year 1851 saw the historic visitation of U.S. Boundary Commissioner John R. Bartlett, who was one of the first to publish descriptions of the Sonoita Valley. He designated it too dangerous and impassible for inhabitants, and suggested the U.S. boundary lie farther north. But by 1853, the Gadsen Purchase made the southeastern corner of Arizona, then the northern part of Mexico, part of the United States. The vast Spanish land grants began to break up as Easterners moved west to homestead and ranch.
Starting around 1857, prospectors mined the silver-rich mountains east of Sonoita and the boom was on. The Patagonia Mountains were filled with rich ore bodies, and by the 1860s, the mining industry procured vast amounts of silver and lead each year. The growth of mining towns such as Mowry, Harshaw, Washington Camp, and Duquesne reflect the extent of the mining boom that last until the early part of the 20th century.
The area got a big boost when the New Mexico & Arizona Railroad connected the area to Mexico in 1882. The villages of Sonoita and Elgin came into being with the arrival of the Benson-to-Nogales Railway, which at one point had three daily stops in Patagonia. Despite the dangers of Apache raids, prospectors headed west to mine silver, gold, lead, copper, and other minerals. Ranchers thrived in Sonoita's rich grasslands and the railroads allowed as many as 3,000 head of cattle a day to be shipped to the East.
A direct rail line from Tucson to Nogales, Sonora, as well as the decline in mining activity, cattle shipping, and population caused segments of the New Mexico & Arizona Railroad to be abandoned between 1926 and 1962. In July 1929, after the tracks were washed out near Patagonia, the bridges were salvaged and the rails picked up between Flux Siding and Patagonia.
The last ore was shipped to the smelter in 1960, and the last of the original railroad line was removed in 1962. The Patagonia Station grounds were donated to the Town of Patagonia and made into a Town Park. The Patagonia Depot was sold in about 1950 to a local businessman, but a local Rotarian purchased it from him. After the Patagonia-Sonoita Club's partial restoration, the Town purchased the building, which still serves as the Town Hall.
Today, the mining camp ghost towns of Harshaw, Mowry, Washington Camp, and Duquesne bear mute testimony to the boom days of yesteryear. Cattle ranches, no longer the vast spreads of the early days, still remain a vital part of the economy and culture. Fourth and fifth generation ranchers and miners still live in the area, as do newcomers such as artists and retirees. Residents have restored historic buildings, and many are in use today, constant reminders of the boom years of yesterday.