Graham, Cochise, and Gila counties were formed. A Century of Dishonor , written by Helen Hunt Jackson, led to the formation of the Indian Rights Association. Santa Fe Railroad crossed northern Arizona. Tenth Calvary was stationed at Fort Whipple. Geronimo and his Apache Raiders surrendered to the US Army.
Copper leads gold and silver in importance in Arizona.
Territorial Capital moves to Phoenix. 1890 Spotted Fever epidemic sweeps Gila River settlement. The Census Bureau declares the end of the American Frontier. The University of Arizona is established in Tucson. Citrus begins large scale commercial growth.