Natural gas tanks, fracking rigs and pipelines share backyards and farmland with people in Weld County, northern Colorado. The area is one of the most densely fracked regions of the United States. Fracking drill rigs first drill deep into the earth to reach oil and gas trapped in shale formations. Horizontal drilling then is used to pump millions of gallons of water, sand and chemicals into the shale to fracture it and release fossil fuels.