Refusing to seek a third term, Slaughter moved out to the ranch with his family and spent the last three decades of his life there. As time went on, the adobe house was expanded and other buildings were added, including a big barn, a commissary, bunkhouses and an icehouse. Three hundred pounds of ice at a time were brought out from the new ice plant in Douglas, enabling John's wife, Viola, to treat everyone to homemade ice cream.
Unlike many ranches in Arizona, the San Bernardino had a natural supply of water from Yaqui river drainage and artesian wells. These springs saved the Slaughter ranch during the severe droughts of 1892 and 1893 when many cattlemen went under. Today, the ponds provide a pleasant spot for visitors to the ranch, which is now a museum.
After Slaughter's death in 1922, the ranch was leased and later sold. Finally it was deeded to the Floyd Johnson Foundation, which has restored the ranch as the Slaughter Ranch Museum.