Voters approved bans on hydraulic fracturing in California, Ohio and Texas this week, most notably in a north Texas town at the heart of the nation's oil and gas boom.
The fracking ban in Denton, a college town of 121,000 about 40 miles north of Dallas, passed with 59% of the vote.
"This is unprecedented," said Bill Kroger, an attorney for the Texas Oil & Gas Assn., which is fighting the ban.
Fracking, or hydraulic fracturing, shoots sand, water and chemicals underground at high pressure to release trapped oil and gas. Environmentalists argue that it contaminates water supplies and that the disposal of fracking wastewater has led to an increase in earthquakes in north Texas and elsewhere across the country.
Other Texas cities have passed laws restricting fracking, Kroger said, but not outright bans. In Denton, fracking opponents formed a coalition of environmentalists and conservatives against what they saw as big government infringing on their health, safety and land rights.
"People recognize this is a mainstream issue," said Adam Briggle, 37, vice president of the group behind the ban, Frack Free Denton.
Briggle, an associate professor of philosophy at the University of North Texas, said the ban was a last resort. He and other organizers had worked for years to strengthen industry regulations, but the industry found ways to work around them, he said.
Texas produced about a third of the country's natural gas last year, the greatest share of any state, according to the U.S. Energy Information Administration. Denton sits atop the Barnett Shale, one of the largest natural gas reserves in the country, with about 275 natural gas wells in the city and scores more on the outskirts.
Last year, the Denton City Council prohibited new wells within 1,200 feet of homes, but many existing wells are closer, Briggle said.
His group's biggest concerns: fracking's impact on air and water and the potential for industrial accidents, especially close to homes and playgrounds.
When Denton residents brought a proposed ban before the City Council in July, it failed, 5 to 2, so they gathered nearly 2,000 signatures to place the issue on Tuesday's ballot.
"What we would like to see is that local communities, the people most vulnerable to the risks of fracking, are empowered to have a greater say over this," Briggle said.
Those who complain that the urban fracking ban infringes on their mineral rights can shift to conventional drilling, Briggle said, or "they can come up with a safer way to maximize their profits that doesn't encroach on other people's rights."
The anti-fracking ordinance is set to take effect Dec. 2.
Energy companies and the state are fighting it. Already this week, separate lawsuits have been filed in two district courts — by Texas Oil & Gas Assn. and the state's General Land Office — challenging and attempting to block the ordinance. The leader of the state commission that approves drilling permits pledged this week to continue issuing them in Denton.
Thomas Phillips, an attorney for the association and former chief justice of the Texas Supreme Court, issued a statement questioning the ordinance's legality.
"Many of the wells in Denton cannot be produced without hydraulic fracturing, so a ban denies many mineral interest owners the right to gain value from their property, despite the state's public policy in favor of developing natural resources," Phillips wrote.
Kroger, the lead lawyer on the case, said the association had asked for a permanent injunction blocking the fracking ban, arguing that it was trumped by state laws that "encourage and promote the practice in the state."
"There's a lot of fears that are not justified or not based in science and fact" about fracking, Kroger said, adding that the legal battle "is really about who should make decisions about how we not only protect mineral rights, but the public."
Denton city officials, including Mayor Chris Watts, who initially voted against it, have vowed to defend the fracking ban in court.
"The democratic process is alive and well in Denton," Watts said in a statement after the vote. "Hydraulic fracturing, as determined by our citizens, will be prohibited in the Denton city limits. The City Council is committed to defending the ordinance."
Fracking bans also passed this week in Athens, Ohio, and San Benito County, Calif.