Besides the Morenci Southern, there were 3' gauge operations by the copper companies.
The outside connection to Morenci from Lordsburg, NM, started out as a 3' gauge railroad Arizona and New Mexico Ry (1883); it was converted to standard gauge 1899-1902. Then sold to El Paso & Southwestern in 1922 and in 1929 the Southern Pacific gained control of the EP&SW.