If one looks carefully, there are 8 electric-powered trains in the various rings of the Bingham Canyon copper mine, not counting the yard to the bottom-left of the frame. Upon closer inspection, one can make out catenary poles from where the shot was taken, down to the yard area, and around every level of the mine until the top few rings. This catenary system is 'portable', which means it can be taken down and re-done easily as the mining operations exhaust certain areas of the mine. Boxcab electric motors power the trains using standard pantographs as well as side-fed pantographs for the areas where the cars are loaded. This mine opened in 1906 and still operates today, though the catenary and electrics were removed from service around 1983. (Data from 'Bingham County Railroads' by Don Strack, April 2011). An original Kodachrome slide from my collection; the photographer was not specified.