After the ratification of the Gadsden Purchase in 1854, the eastern portion of Santa Cruz County became part of the United States. In 1856 US Army Major Enoch Steen who was stationed in Santa Fe, NM was given orders to establish a military post to defend the citizens of Tucson from the Apache. Upon his arrival in the area along with Captain Richard Ewell, the two officers decided that the Tucson valley could not sustain a military post. They rode south along the Santa Cruz River with two companies of United States Dragoons and established Camp Moore near Calabasas, at the confluence of the Santa Cruz River and Sonoita Creek.
The citizens of Tucson were disappointed when the troops left the immediate area and started a campaign to bring the troops closer home. After several months of receiving complaints at the Santa Fe Headquarters, Major Steen was ordered to locate a military post closer to Tucson. Captain Ewell chose the location for the next encampment at the headwaters of the Sonoita Creek (about 9 miles northeast from Patagonia along Highway 82). It was named Fort Buchanan in honor of the president.
The new location afforded ample forage for the horses plus it was less prone to mosquitoes than Camp Moore and was in the corridor used by the Apache to raid into Sonora. Unfortunately, according to the citizens, it was still not close enough to Tucson so they continued to complain until Fort Buchanan was abandoned by the army in 1861. (In case you are interested, Tucsonians eventually got their own Camp Lowell which became Fort Lowell in 1873.)
Following the establishment of Fort Buchanan in 1857, the Sonoita Creek Valley was soon inhabited by farmers, merchants and miners making the area eligible to participate in the 1860 Census. In summary, the total population for Fort Buchanan and the Sonoita Creek Valley area was listed at 201. The 2 companies of dragoons at Fort Buchanan accounted for 92 soldiers, 26 of whom were born in Ireland. There were 43 civilians living at Fort Buchanan and 66 civilians along Sonoita Creek for a total of 109. Of the civilians, 57 were adult males, 26 adult females and 26 children. Of the civilian population, 47 were born in New Mexico or Mexico.
Thanks to the Arizona Historical Society in Tucson for maintaining copies of the “Census-Territories of New Mexico and Arizona” (US Govt Print Office 1965, 312.979 U58). You can click on the links below to view the individual census records. In general, the civilian residents are listed in alphabetical order as opposed to by location or household which is the order of the typical census document.