If you want to see the future of the shale industry — what today's drilling rush will leave behind — come to Bradford, Pennsylvania. A small city, it was home to one of America's first energy booms, producing over three quarters of the world's oil in 1877. A wooden oil rig towering over a local museum commemorates those heady days, marking the first “billion dollar oil field” in the world. But times have changed dramatically in Bradford. Eventually, the oil runs out.