Newly added US data center capacity slows down considerably in Q4 2025, as market struggles to keep up with explosive demand

25 gigawatts (GW) of new data center capacity was added to the funnel in Q4 2025, half of Q3 additions, signaling a challenging development environment and a focus on the existing pipeline, according to a new analysis from Wood Mackenzie.

At the end of 2025, the US disclosed data center project pipeline reached 241 GW, 33% of which is under active development, according to Wood Mackenzie's latest "US data center pipeline" report. This is significant growth compared to the 93 GW pipeline that ended 2024.

However, the market is struggling to keep pace with new commitments.

"Developers shifted to focusing on the existing pipeline at the end of last year as opposed to new projects, as load queue constraints weighed on the market," said Ben Hertz-Shargel, Global Head of Grid Edge for Wood Mackenzie. "Much of the planned capacity belongs to new developers with a small number of massive, speculative projects, disproportionately targeting the South and Southwest."

Cost Dynamics Shift

In a notable first, per-megawatt costs declined in Q4 2025 after steady increases throughout 2024. However, rack power densification has resulted in cost per square foot rising even as cost per MW declined, reflecting the industry's shift toward more energy-dense facilities to maximize efficiency and reduce inference latency.

The capex growth slowdown in 2026 represents a significant shift, with the largest developers projected to invest US$94 billion more than in 2025 - just 58% of last year's growth. Unlike other hyperscalers that maintain net positive cash positions, Oracle has gone deeply into debt funding its Stargate campuses, many of which rely heavily on behind-the-meter generation.

Regional Shifts and Developer Landscape

While Texas maintained its lead in total pipeline capacity, the market saw significant relative growth in emerging markets. New Mexico, Indiana, and Wyoming experienced the greatest proportional growth in Q4 2025, driven primarily by access to natural gas supply.

The developer landscape is increasingly dominated by new entrants pursuing speculative mega-projects. Planned capacity is now weighted toward new developers with a small number of massive projects targeting the South and Southwest, accounting for 39% of the total pipeline.

Grid Constraints and Energy Commitments

Large load capacity that has signed construction or electricity supply agreements has reached 183 GW, equivalent to 22% of 2025 US peak load, more than regional grids can handle. Utilities in ERCOT and PJM are responsible for 72% of large load capacity commitments, though a majority of committed load (58%) is contracted with wires-only utilities who have no responsibility to ensure adequate supply.

PJM faces particular challenges, with utility large load commitments three times as large as the accredited capacity in PJM's risked generation queue, including pre- and post-ISA projects. This mismatch highlights the growing tension between data center demand and available generation capacity.

Texas has four times more planned data center capacity with onsite generation than any other state. In PJM states Pennsylvania and Virginia, the lion's share of onsite generation will be grid-tied, whereas onsite generation in states such as Texas, Wyoming and New Mexico will be invisible to the grid, if not fully off-grid.

Policy Landscape Creating New Challenges

New data center policy proposals are scrambling success criteria for developers, prizing state relationships for generators and requiring strong balance sheets as well as power expertise for data center developers. The White House, PJM, and PJM governors are aligned on market reforms, though key details about an upcoming backstop auction remain unclear.

New interconnection rules proposed in SPP and ERCOT pose operational risks to data centers, particularly voltage ride-through requirements and exposure to frequent curtailment. NERC is working toward a national standard for ride-through, which would make compliance a US-wide challenge for data center operators.

"New data centers must contract with new generation or face non-firm transmission service," Hertz-Shargel added. "This creates diesel supply and generator runtime risk that could cause hesitation on data center development in these regions."

The slowdown in new capacity additions, combined with decelerating capex growth and increasing policy complexity, suggests the US data center market is entering a maturation phase where execution on existing projects takes priority over pipeline growth.