Hydraulic fracturing in the United States

Hydraulic fracturing in the United States began in 1949.[1] According to the US Department of Energy, as of 2013 at least two million oil and gas wells in the US have been hydraulically fractured, and that currently about 95% of completed oil and gas wells in the US are being hydraulically fractured. Hydraulically fractured wells make up 43% of the oil and 67% of the current natural gas production in the United States.[2] Environmental safety and health concerns about hydraulic fracturing emerged in the 1980s, and are still being debated at the state and federal levels.[3][4]