The densest cluster of data centers in the world sits just east of the Blue Ridge and the dark places beyond it. Drag the slider to see what the county's own pipeline numbers could mean overhead.
Loudoun's first data center opened in 1997. In 2000 the county zoned the use as an office park, which let data centers rise by right for a quarter century. The result is a corridor around Ashburn that planners and advocates both describe as the world's densest.
Most existing buildings went up between 2019 and 2024. In 2025 alone the county issued permits for more than 10 million square feet, its highest one-year total. Newer permits average about 339,000 square feet per building, against 234,000 for the existing stock.
Why the pipeline matters. Space approved but not built will arrive without another public vote in most cases. From 2022 to May 2026 the Board of Supervisors approved 32 of 39 data center legislative applications. The county stresses that not every approved building will be built.
The Ashburn core was built on former fields and office parks. The next wave is pressing against the edges of the county: the Transition Policy Area, the Goose Creek corridor, and the power lines that feed everything.
Spring Valley Technology Park, proposed near Goose Creek with on-site power generation, would clear 342 acres of mature forest, according to the Loudoun Wildlife Conservancy. The Planning Commission voted unanimously to recommend denial. The applicant has since asked the Board to defer the hearing indefinitely.
An earlier Goose Creek fight flagged a rare mafic barrens community and wood turtle habitat, plus stormwater and erosion into the creek.
Habitat lossDominion's proposed Golden-to-Mars line is 500 kV on poles about 165 feet tall. It would need wide tree clearance and passes near homes and two schools on the preferred route. Dominion says it must be energized by 2028. More than 1,000 written comments reached the State Corporation Commission.
The county asks for burial of segments within 500 feet of homes and schools, but the SCC, not the county, picks routes.
Land and treesData centers drew nearly 952 million gallons of potable water in 2025, about three times the amount four years earlier, in addition to reclaimed water. Loudoun Water began its reclaimed program for data centers in 2010.
Elsewhere in Northern Virginia, reporting has put the draw at up to 5 million gallons a day for one large evaporatively cooled site.
Growing fastA state legislative review found that in a worst case, backup generators in the region could emit about 9,000 tons of nitrogen oxides, about half of what all sources typically emit in Northern Virginia in a year. Northern Virginia is still under an ozone non-attainment designation.
Virginia DEQ relaxed its guidance on generator use by data centers in January 2026.
Health stakesAfter a power failure forced a Sterling campus onto diesel generators, neighbors told the Board of Supervisors of constant hum and fumes. The operator said regulators found emissions well below permitted levels and that the system is temporary.
Dominion has warned that generator use may become more frequent as grid demand grows.
Neighbors noticeSecurity lighting, parking lots and lit façades run all night. Loudoun Wildlife Conservancy says wildlife suffers most from disrupted nightscapes and wants strict lighting standards applied countywide, including on data center sites, to protect corridors and natural areas.
See the next sectionA data center is lit all night, every night. Whether that light stays on the ground or leaks into the sky depends on the fixture. Toggle the lamp to see the difference.
Downward, shielded fixtures with a sharp cutoff. Color temperature of 3000K or lower. Motion sensors and dimming after hours. Roughly 2 lux in parking areas.
County planning staff have cited the county's night-sky policy, which excludes upward-facing data center lighting, when urging denial of an uplit sign.
Light spreads far. In 2010, before most of today's build-out, Northern Virginia Magazine reported that amateur astronomers at a site in Fauquier County found roughly a third of the northern sky washed out by skyglow from Loudoun and Prince William. Both counties have added enormous amounts of development since.
Virginia's International Dark Sky Park in Fauquier County lies west of the Loudoun and Prince William corridor. Its dark sky is the kind of resource that spreading glow can wear down.
Dark places along the ridges and in the Highlands are far from the corridor, but skyglow travels, and new campuses are being proposed farther out. These pages track the ones at risk.
Proposals are moving west. Fauquier County faces its own data center applications, and Loudoun's rural policy area, about two-thirds of the county, does not allow the use.
Distances are approximate. No published study measures how much of today's skyglow at Sky Meadows comes from data centers specifically. Independent sky-brightness monitoring would settle it.
Any honest account has to start here. Data centers pay for a lot of Loudoun.
About $1.2 billion in property tax revenue in fiscal 2026, 39% of the budget, projected to reach $1.3 billion and 40% in 2027. More than 17,000 direct and indirect jobs.
A budget that tracks one industry. A state sales-tax exemption for data center equipment that cost more than $920 million in fiscal 2023 per Virginia's legislative audit. Costs that fall on forests, air, water, power customers and the night, none of which appear on a balance sheet.
Figures above come from the county's 2026 summary. Other outlets report different shares, up to about 45% of the budget, depending on the year and measure.
Decisions in the next year will shape the whole corridor. Status can change weekly, so check the county's pages before you act.
First Loudoun data center. The zoning administrator classifies data centers as office parks, opening the door to by-right development.
Standards are streamlined. About 14 new data centers a year are permitted, increasingly hyperscale.
Phase 1 of the Data Center Standards and Locations project ends by-right approval. New data centers need a special exception, a public hearing and a Board vote. The same day, the Board grandfathers applications already in the pipeline.
Virginia DEQ revises guidance relaxing restrictions on generator use by data centers.
The Board votes to consider pausing legislative data center and substation applications for up to 12 months while Phase 2 is written. The County Attorney says a blanket moratorium is not legal, and the pause would not touch at least 17 grandfathered cases covering more than 11 million square feet.
The formal pause resolution is deferred to the Board's November 17 meeting. Two supervisors have also asked to rescind the grandfathering resolution, which would send roughly 20 projects to full review.
Phase 2 standards are written and open for public input. Topics include siting, substations, on-site generation, battery storage, noise, building height and parking. Lighting is not named in the county's summary.
Statewide, advocates are pressing for a moratorium in the 2027 General Assembly, and Governor Spanberger issued an executive order on a Virginia Data Center Accountability Framework in September. Check current status before relying on this timeline.
None of this stops the industry. It asks the Phase 2 rules and the state to price in what is now free.
Require shielded fixtures, 3000K or warmer, motion sensing and dimming after hours on every site, with a lighting audit before approval.
Set a total-light budget per site and per corridor, and fund independent sky-brightness monitoring.
Send pipeline projects through full review so they meet the new standards.
Keep data centers out of the rural policy area and intact forest. Require stormwater and buffer standards along Goose Creek.
Notice, monitoring and public reporting of generator use, with cleaner equipment as the default.
Underground or co-locate transmission in existing corridors, and require new clean power for new load.
Support a pause on new hyperscale approvals until air, water and grid costs are planned for.
Comment on Phase 2, attend Planning Commission and Board hearings, and join Piedmont Environmental Council and Loudoun Wildlife Conservancy action alerts.
The corridor is built. What happens in the next year decides how far the glow, the clearing and the power lines creep toward the dark places to the west.