Adds details on turnout in paragraphs 4-6

By Valerie Volcovici and Lisa Baertlein

July 18 (Reuters) - Opponents of the rapid buildout of data centers held 142 protests across 42 states on Saturday in the first nationwide effort to channel anger at the AI infrastructure expansion that has ramped up over the past year and roiled local politics.

The protests were coordinated by HumansFirst, co-founded by a former leader of the modern-day Tea Party. She compares growing opposition to data centers to the right-wing populist movement that emerged in 2009 to protest what it saw as excessive taxation and government overreach.

Protesters rallied against what HumansFirst calls the “unaccountable” buildout of data centers and “unacceptable infringement on our liberty.”

In Fredericksburg, Virginia, one young man carried a sign reading, "We thrive on water not data." In Atlanta, a small knot of protesters wielded signs reading, "Georgia never voted for hyperscale AI data centers."

Nationwide and city-specific counts of protesters were not immediately available, said Chris Barron, president at Right Turn Strategies, who is handling press relations for HumansFirst.

Attendance was lower than expected in some rural areas and major cities such as Atlanta, local organizers told Reuters. But HumansFirst praised the efforts of community activists. "We were thrilled with the turnout," Barron said.

Data center opposition is among the few issues uniting Americans across ideological lines, with just a third of Americans approving of the pace of data center construction in the U.S., according to a June Reuters/Ipsos poll. Only 14% of respondents would support a data center being built in their community to support artificial intelligence projects for technology firms such as Meta META.O, Alphabet GOOGL.O, Amazon AMZN.O, Microsoft MSFT.O and Elon Musk's xAI.

"The data center industry is continuing to work with policymakers, stakeholders, and residents to ensure data centers strengthen, not strain, the areas where they operate — while mitigating any negative impacts to households and businesses," said Josh Levi, president of the Data Center Coalition, the industry's association and lobbying group.

RED AND BLUE STATES REPRESENTED

Although HumansFirst co-founder Amy Kremer compared her current efforts to the Tea Party movement’s early days in 2009, she said the anger against data centers is nonpartisan.

"They just woke up one day and found out they're going to have this monstrosity in their community, and they don't want it," said Kremer, who predicted data centers will be a defining issue in November’s midterm elections and the 2028 presidential race.

Kremer has criticized Republicans for giving Big Tech a "free pass," but she and some organizers also said they do not support policies like moratoriums on data center approvals like the one adopted by the Democratic state of New York.

Demands made by organizers from the groups involved include transparency in the development process, protection of resources and environmental health, community benefits such as the creation of well-paying union jobs, and a way to hold developers accountable if they break their promises.

The Republican stronghold of Texas, a hotspot for data center development, hosted 18 protest events, the most of any state. The battleground state of Georgia had 11 rallies. Democratic-dominated California had eight, while the swing state of Pennsylvania and the Republican-leaning states of Florida and Indiana came in at seven each.

Saturday's Atlanta protest, one of a number of similar actions this month, attracted about a dozen participants who traveled from smaller Georgia towns where the largest data centers are being built, said Jake Watts, 26, a volunteer at that event.

Left-leaning Ivan DelSol, 54, helped lead a protest in the California desert's Imperial County, where a proposed data center project could use 260 million gallons (984 million liters) of water per year from the Colorado River.

"It's dystopian that you would use this much fresh water for AI," said DelSol, who later added around 50 people attended despite temperatures that soared above 100 degrees Fahrenheit (38 degrees Celsius).

Although water is frequently cited as a top public concern, especially in water-stressed regions, the data center industry says its water use is not as significant as other industries.

In Tyler, Texas, first-time activist and self-described "political nomad" Eva Cardona, 31, organized a protest that also drew about a dozen people.

"I've been hearing about unregulated AI and the rapid growth was alarming me. I wanted to do something more hands-on than just your standard Facebook post," Cardona said.

(Reporting by Valerie Volcovici in Washington. Lisa Baertlein in Los Angeles and Evelyn Hockstein in Fredericksburg, Virginia; Editing by Stephen Coates, Chris Reese and Sergio Non)

((valerie.volcovici@thomsonreuters.com;))