HARRISBURG, Pennsylvania - Building trades unions - long fashioned as the voice of the American worker - are now intertwined with the richest companies in the world as they create America's artificial intelligence economy.
Unionised workers are employed on a huge number of massive data centre projects and scrambling to recruit new apprentices to feed the explosive demand.
They've also become an ally of tech giants and tech-friendly government officials, echoing the talking point that the United States is in a critical national security race with China for AI superiority.
Unions are a visible force in helping counter fierce opposition in communities and hostile legislation in Congress and legislatures, often aligning with traditional Republican pro-business constituencies and forcing Democrats to choose between them and progressives who want to take a harder line.
Unions have aggressively answered complaints about data centres in ways that executives at tech giants and the development firms rarely do, unafraid to bluntly confront concerns about energy and water shortages, rising electric and water bills, or noise and quality-of-life objections.
"When people say, you know, 'data centres are the root of all evil,' we're just saying, 'look, they do create a hell of a lot of construction jobs, which we live and work in your communities,'" said Rob Bair, president of the Pennsylvania Building and Construction Trades Council.
Instead of "being just a blunt 'no,'" Bair said, communities should figure out what they need and ask the tech companies for it - such as improvements to the project's plans or millions of dollars for local schools. "If you don't ask, you're never gonna get," he said.
With data centre construction accelerating, unions are expanding training centres and seeing their ranks grow faster than many union leaders have ever seen.
Unions in a number of states are reporting skyrocketing man hours, apprentice classes doubling in size and training centres undergoing expansions in anticipation of more work coming.
Data centres consume at least 40 per cent of work hours done by members of the Columbus-Central Ohio Building and Construction Trades Council, a top official, Dorsey Hager, estimated. It's at least 50 per cent for the International Brotherhood of Electrical Workers Local 26 in metropolitan Washington, DC, spokesperson Don Slaiman said.
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The umbrella North America's Building Trades Unions said it hit a record number of members and apprentices in 2025.
The organisation's president, Sean McGarvey, compared it to the build trades' expansion in the 1950s. He attributes today's growth to data centres, power plants and legislation under former President Joe Biden that subsidised the construction of semiconductor and electric vehicle battery factories, energy efficiency projects and grid transmission improvements.
Data centres' voracious energy needs are setting off a power plant construction boom and delivering a one-two punch of new life to unions whose members also build and maintain boilers, ductwork, pipelines and other power infrastructure.
The Boilermakers Local 154, whose members have watched power plants shut down in southwestern Pennsylvania, went from recruiting zero apprentices for four years to now assembling a class of over 200 - and they need more, union official Shawn Steffee said.
For their part, tech giants say they need to train hundreds of thousands more workers in skilled trades. They are spending tens of millions of dollars on training programs, including partnerships with unions that they hire to build their multibillion-dollar projects.
"Across the country, highly skilled union construction workers are laying the foundation for the AI economy," Sam Altman, co-founder and CEO of OpenAI, said in a joint statement in March with McGarvey's organisation.
Google said the majority of labour used to build its data centres is unionised, and pointed to a US$10 million (S$12.7 million) grant to a union-backed electricians training programme that it said would help expand the electrician workforce pipeline by 70 per cent.
Mark McManus, the general president of the United Association of Union Plumbers and Pipefitters, whose members work on pipelines, data centres and power plants, acknowledged criticism that organised labour is getting in bed with the richest, most powerful companies in the world.
But he rejected it as unrealistic.
"If we chose as a union to have a moratorium on building the data centres because we didn't believe it was right for America, the data centres would still be getting built," McManus said. "They're not stopping because of organised labour."
His union has a strong relationship with tech companies, is hitting all-time highs in membership and, based on an internal survey, has members working on over 90 per cent of the data centre projects in the United States.
"That's a market share that we don't have in a lot of other industries," McManus said. "So it's pretty near and dear to us."
It's difficult to pin down exactly how many data centre projects involve union labour. An Associated General Contractors of America survey late last year suggested that the labour composition of data centre construction likely mirrors the makeup of commercial construction, which is roughly one-third union, an AGC spokesperson said.
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National unions have negotiated labour agreements on major projects, including an Oracle and OpenAI Stargate campus in Michigan and the Project Blue data centre campus in Arizona, with more in the works.
When Gov. Josh Shapiro stood with Amazon executives to announce that the tech giant would spend US$20 billion on two data centre projects in eastern Pennsylvania, Bair stood with them.
"This is really unique, what we're building here in this commonwealth. People coming together with common purpose to get stuff done," Shapiro said.
In statehouses, unions have worked against Maine's since-vetoed proposal for a statewide data centre moratorium; standards proposed in Illinois, including requiring data centres to supply their own energy; and an end to Virginia's sales tax exemption that helped make it the world's biggest data centre destination.
Pennsylvania state Sen. Katie Muth said it has been difficult to collect support from fellow Democrats for her legislation to regulate data centres when it is competing with union-backed legislation that she views as weaker.
"The unions don't want to promote anything that would impede data centre development," Muth said.
Union representatives have made their presence felt at packed council meetings in municipal buildings from St. Louis to Spring City, Pennsylvania.
Sometimes it's not in a good way.
Speaking to the City Council in Joliet, Illinois, Alicia Morales complained that union members - who sat in the front row holding "vote yes for union jobs" signs - had been disrespectful and "bullied a lot of people" entering the meeting.
Sometimes, union representatives are the only people in a packed municipal meeting room to speak in favour of a project.
"I just want to commend you guys, thanks for being the adults in the room," Chuck Curry, the president of Ironworkers Local 395, told City Council members in Hobart, Indiana, at a January meeting on an Amazon data centre. "Knowing the tax structure, knowing business, that most of the people here don't know."
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