The 2026 ENR Top 500 Design Firms list is the most lopsided ranking in years. Domestic design revenue across the list grew 8.1% to $136.3 billion. International revenue grew 3.2% to $22.4 billion. The combined total, $158.7 billion, is up 7.4% from the prior year. Almost all of that growth came from one place: AI infrastructure.
The shift is visible at the very top. Jacobs returned to No. 1 after a year as runner-up, pulled there by an unusually broad sector footprint that includes water, defense and a fast-growing data center practice. AECOM, the firm that displaced Jacobs in 2025, dropped back to No. 2 even as its own revenue grew. The same pattern shows up in the pure-design rankings, where Kimley-Horn climbed to No. 4 on the strength of mission-critical and site-civil work.
The data-center tail is wagging the firm
ENR’s telecom market segment, which captures most data-center design work, grew 31.3% between 2024 and 2025. Stacked over two years, that segment is up nearly 87%. No other ENR market has expanded that fast since the data center as a building type started showing up in the rankings.
That single category now drives the firm-level decisions you’re seeing in the trade press. Stantec has been pulling mission-critical leadership from across its U.S. offices. HDR rebranded an internal practice as “AI infrastructure” to consolidate hyperscaler work. Smaller firms are getting acquired specifically for their data-center experience. None of this is rumor anymore. It’s in the financials.
It also bends the rest of the list. Some 200 of the Top 500 firms touched data-center work last year. The ones that didn’t lagged the index. Several middle-tier firms that posted flat 2025 numbers told ENR they couldn’t staff data-center pursuits fast enough and watched competitors take work they’d have bid on five years ago.
The risk underneath the growth
Demand keeps printing. Power doesn’t. The Lawrence Berkeley National Lab’s queue data shows new interconnection requests now spending an average of five years waiting for transmission capacity. Transformer lead times have stretched from 30 months to five years. Roughly half of the data centers slated to open in 2026 are reporting some combination of delay or scope reduction tied to grid access. That same dynamic shows up in our coverage of how the data center construction pipeline is colliding with the power grid.
Forecasts also assume the spend persists. One bank-side estimate has $1.75 trillion in AI-related infrastructure outlays through 2027. That’s a real number if hyperscalers keep building at current pace. It is also not contracted, and one or two large pullbacks would reset the entire telecom-segment growth rate.
What to watch on next year’s list
Three things. First, whether AECOM or another diversified firm reclaims No. 1, or whether Jacobs’s data-center concentration locks it in. Second, whether smaller pure-design firms can keep monetizing the AI tail when hyperscalers consolidate vendor lists. And third, whether the international column, which grew at less than half the U.S. rate, accelerates as European and Asian hyperscalers scale up their own building campaigns.
The 2026 Top 500 is a strong year. It’s also a concentrated one. Reporting drawn from ENR’s annual Top 500 Design Firms analysis.