Hydraulic fracturing -- the controversial process of cracking rock with water, sand and chemicals -- is booming, and will continue no matter who's president.

Obama has moved to tighten federal regulations on fracking, and will likely continue to do so if re-elected. Romney would leave the regulations up to the states, which are tightening the rules anyway in response to public pressure. Some say state regulators tend to be more favorable to industry.

But neither increased state nor federal regulations are thought to be enough to seriously reduce the number of wells that get fracked each year. Nor will they be enough to satisfy the most virulent critics, who fear groundwater contamination and want the practice banned altogether.

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