Advocates of the ballot measures say the wins provide momentum for the national movement to ban hydraulic fracturing, or fracking, the energy industry practice of injecting wells with millions of gallons of water and chemicals to release trapped oil and gas. (Take the quiz: "What You Don't Know About Natural Gas.")

But oil industry representatives said the Election Day outcome means little because the cities that halted fracking have little or no oil and gas production. In contrast, the Broomfield City Council had already decided in August to enter into a memorandum of understanding with the energy company Sovereign, allowing drilling of 21 wells as long as Broomfield's new, stringent drilling standards are met.

The attempted moratorium in Broomfield failed by