Each dot is a data centre: choose one to see its dates.
An AI data centre takes about two years to build
Epoch AI follows 93 large AI data centres from satellite images, permits and announcements. For each it records when land clearing began and when the first building started drawing power for servers.
Of the 53 sites built from scratch and already running, the median is 26 months. For the 20 that began operating in 2025 it is 24 months, and the middle half of the sites falls between 19 and 31 months; the fastest of them, Colossus 2, took 7.7 months, the slowest, AWS Berwick, 50 months.
Colossus 2 was built next to an existing building; Epoch notes a battery facility at the building and gas turbines at a Duke facility nearby in Mississippi. The slowest of all 53, Microsoft SAT40, took 65 months (started in 2018).
From the interconnection agreement, a power plant needs a median of 31 months
Berkeley Lab, a US Department of Energy national laboratory, tracks the interconnection queues of American power plants. The median from signed interconnection agreement to operation was 31 months for plants that came online in 2025, in a sample covering 1,492 projects across all years, 142 of them from 2025.
The report attributes the length of this stage largely to things outside the interconnection process: procurement and the contract to sell the power, permitting, and the completion of transmission lines.
Before the agreement, a request waits a median of 45 months
For agreements signed in 2025, the median from filing the request to signing the agreement was 45 months. The sample covers 4,929 requests across all years, 519 with an agreement in 2025. The report notes that agreement dates for 2023–2025 are missing for several regions and that the sample comes largely from ERCOT, where durations are typically shorter. From request to operation the median is 61 months for plants that came online in 2025 (3,310 projects across all years, 296 from 2025), against 36 in 2015 and 22 in 2008: 2.8 times as long as in 2008.
The three medians come from different samples and do not form a single timeline. Of the requests filed in 2000–2020, only 19% (13% of capacity) were operating by the end of 2025.
The missing clock: the one before the bulldozer
The Berkeley Lab report covers only the connection of power plants to the transmission grid, not distribution and not consumers. Epoch starts measuring at land clearing. For the period between the decision to build a data centre, its request for power and the first bulldozer, no comparable public measurement exists.
That does not mean a data centre waits five years for the grid. It means the part of its clock that comes before the bulldozer does not show in these data.