Cochise County was carved Removing off in 1881 from the easternmost portion of Pima County during a formative period in the American Southwest .

Pima County and later Cochise County were the primary battleground for most of the resulting Causation quarter-century of warfare Hostile_encounter , which was almost constant in the region until the late 1880s .

President Ronald Reagan declared Expressing_publicly Cochise , Gila , Graham , Greenlee , Pima , Pinal , Santa Cruz and Yavapai counties a `` major disaster area '' .