Ireland’s economic footprint in the United States is growing again.
Irish companies are planning at least $6.1 billion in new investments in the U.S., expanding across industries including technology, manufacturing, and food and nutrition. The spending push, unfolding as the U.S. ramps up infrastructure for artificial intelligence and other energy-intensive technologies, reflects a deepening economic relationship between the two countries. The move was also touted in advance of the annual St. Patrick’s Day visit by Micheál Martin, Ireland’s taoiseach, or prime minister, to the White House, after calls by President Trump for foreign trading partners to invest in the United States.
Ireland’s longstanding ties to the United States—and the millions of Americans who claim Irish heritage—are a regular feature of mid-March political rhetoric. While Trump has pointed to Irish business investment and the number of U.S. presidents with Irish ancestry, New York Mayor Zohran Mamdani used a St. Patrick’s Day speech to highlight Ireland’s role in labor organizing and anti-colonial solidarity movements.
But Ireland’s economic ties to the United States extend well beyond political symbolism. Ireland is already the fifth-largest source of foreign direct investment in the country, with the top 10 Irish companies employing more than 125,000 people in the United States, according to Enterprise Ireland, the Irish government’s business development arm.
“That speaks to their level of confidence in the U.S. market and the size of the growth opportunity,” says Enterprise Ireland CEO Jenny Melia. In recent years, Irish businesses have been investing in particular in the U.S. data center boom, drawing on decades of relationships with major American tech firms that run European operations from Ireland. The Emerald Isle has also developed experience hosting data centers and managing their effect on the electrical grid and other resources—but also faces increased opposition to further build-outs at home due to those very impacts.
“Irish companies have really honed and perfected their skillset and talent in those areas over the last 20 [to] 30 years, and in fact, have led out on data center builds right across Ireland and right across Europe,” Melia says.
Now, they’re increasingly turning their eyes to the United States, where Irish companies and a growing number of American employees are working to produce a variety of infrastructure, tools, and materials to fuel the growth in data centers, driven in part by the rush of investment into artificial intelligence.
“It’s really supply and demand,” says David Maher, senior vice president at Limerick-based H&MV Engineering. “And it’s providing really good opportunity at the moment.”
H&MV builds infrastructure that connects big energy consumers like data centers, as well as generating facilities like solar power sites, to utilities and the broader electrical grid. It’s seen revenue rise to more than $1 billion per year, and in January announced the acquisition of Amarillo, Texas-based Cooke Power Services.
Maher says demand for the company’s expertise will extend beyond the immediate data center boom as utilities continue deploying technologies like renewables and battery storage. That outlook is echoed by other Irish companies expanding into the United States, who also point to the need to continually revamp existing data centers to support new technology and improve efficiency.
“I don’t see this as a short-term industry—it’s only just starting,” says Orla Good, commercial director at Portwest, a Westport, Ireland-based company that’s among the leading makers of protective workwear. “Once, I’m sure, the capacity has been built, there will be retrofitting on some of the older data centers in order to catch them up technology-wise with the newer ones.”
Portwest operates a distribution center in Kentucky, managing logistics around gear like innovative lightweight arc-protection wear that can safeguard workers from electricity while reducing heat risk. The company invested $4.4 million in the 71,000-square-foot site and plans to open a second site in Nevada this year, and it anticipates U.S. headcount to rise from just over 100 today to more than 200 within the next two years.
Irish companies like Portwest didn’t arrive at their technical expertise by happenstance, Good says.
“Ireland is very strong historically on adapting to new ways of working, innovative in the form of creative ideas and problem solving, and we have a strong heritage of STEM in our education system,” she says.
And that culture is a good fit for collaboration with American businesses, says Enterprise Ireland’s Melia.
“I often say we love to find a problem and then we love to solve it,” she says. “And I think that mixes really well with the go-and-get-up attitude that we see in the United States.”
Other Ireland-based companies are also contributing to the infrastructure needed to get new data centers up and running—and existing ones revamped—while employing increasing numbers of workers in the United States.
“There’s a huge volume of work coming down the road,” says J.J. O’Hara, CEO of Irish construction innovation center Future Cast. “Every one of the data centers that was built 10 years or older, is going to have to be retrofitted.”
Electrical equipment maker CEL Critical Power in 2025 invested more than $40 million in a new 400,000-square-foot manufacturing plant in Williamsburg, Virginia, and building material giant Kingspan expanded sites in multiple states in 2025, with additional expansions targeted for 2026. The company employs about 2,700 people across 17 states.
Irish companies are also delivering technologies that can make building and operating data centers and other structures more efficient. Ireland’s Midland Steel last year signed an exclusive deal with Nucor, the largest U.S. steel producer, to license its FasterFix rebar technology, which can make build times dramatically faster and work with Nucor’s existing steel recycling systems to cut waste.
Evercam, which makes technology to monitor construction sites with cameras and drones and verify that what is being built matches plans created in building information modeling (BIM) software, recently announced plans to expand in North America. Operating across multiple continents helps Evercam innovate, says managing director Nick Leysath, allowing the company to share practices and research across different markets.
“The advantage of operating globally is really being able to knowledge share across these markets,” he says, which can include transposing data protection policies from Europe and the Middle East to the United States and doing U.S.-based R&D informed by partnerships with robotics and AI startups.
Years of workplace ties—and the extensive cultural connections between the United States and Ireland, particularly visible around St. Patrick’s Day—makes cross-Atlantic collaboration easy, Melia says.
“It’s a perfect mix of a heritage and business culture across our two countries,” she says.