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Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Data Center Alley is the informal name for the dense concentration of data centers centered on Ashburn in Loudoun County, Virginia. It is not a city, a single campus, or an area with a defined legal boundary. The name can also refer more broadly to the Northern Virginia data-center region, so figures about its size depend on which geography and facilities are being counted.
Where is Data Center Alley?
The name most often points to Ashburn and the surrounding parts of Loudoun County, in Northern Virginia, west of Washington, D.C. In regional discussions, it may describe a wider network of data centers across Northern Virginia. Loudoun County and the Northern Virginia Regional Commission use the term at different geographic scales; neither source establishes a precise boundary. Loudoun County’s account focuses on its own Ashburn-centered cluster, while the Northern Virginia Regional Commission describes the region.
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That distinction matters when comparing statistics. A county count of buildings or square footage is not interchangeable with a regional count of data centers, and the numbers should not be added together.
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Why did so many data centers develop around Ashburn?
Loudoun County traces the region’s internet-infrastructure history to 1992, when Metropolitan Fiber Systems and UUNet connected local fiber networks in a Vienna parking garage to create MAE East, a commercial Internet Exchange Point. AOL opened its global headquarters in Ashburn in 1996, followed by UUNet’s headquarters there in 1998. The county says these developments helped establish the fiber infrastructure that later attracted data centers.
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The county also cites Ashburn’s proximity to Washington and federal customers, a major international airport, available land, power, a qualified workforce, and permitting conditions. It describes favorable zoning and expedited approvals as contributors to a surge in development from 2007 to 2016. These are the county’s explanations, not a ranked analysis of how much each factor independently caused growth.
A Loudoun County policy document says a 2008 marketing campaign promoting low latency helped popularize the label “Data Center Alley.” That is the county document’s account of the name’s promotion, not proof of the phrase’s first-ever use. The county’s history and data-center information provide its account.
How large is the data-center cluster?
Counts vary because sources cover different territories and distinguish buildings, operating facilities, construction, and approved projects. These dated figures illustrate those differences:
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| Figure | Scope and status | Source and date |
|---|---|---|
| Approximately 233 buildings and 56.5 million square feet | Loudoun County; existing buildings that are built or under construction | Loudoun County, as of March 1, 2026 |
| Approximately 35.7 million square feet | Loudoun County; approved data-center use not yet built. The county says the total may decrease and could amount to approximately 115 additional buildings. | Loudoun County, as of March 1, 2026 |
| More than 250 data centers | Northern Virginia region; the geographic scope and counting basis differ from the county’s building and square-footage figures. | Northern Virginia Regional Commission, page accessed October 7, 2026 |
| More than 17,000 data-center-related jobs | Loudoun County; direct and indirect jobs, not facility payroll alone | Loudoun County, page updated with its 2026 snapshot |
The county’s economic-development office separately lists more than 25 million square feet operational and more than 12,000 jobs. Those are that office’s profile figures, with a different scope or date from the county’s history-page snapshot; operational square footage is also not the same measure as buildings built or under construction. Loudoun County Economic Development publishes the profile.
What has Data Center Alley meant for Loudoun County?
The sector is a major source of county revenue. Loudoun County reported $1.2 billion in data-center real and personal property tax revenue for FY 2026, equal to 39% of its overall budget. Its adopted FY 2027 budget projected $1.3 billion, or 40% of the total budget; that is a forecast, not a completed fiscal-year result. The county’s data-center information provides the figures and their fiscal context.
The county also identifies community concerns including noise, air quality, water use, land values, community aesthetics, and energy infrastructure. Those concerns can depend on a facility’s location, design, equipment, and operations; they should not be assumed to apply identically to every site.
How is local review changing?
Loudoun County says it ended by-right data-center development in 2025. New development proposals now require special-exception approval, which means they go through a local review process rather than proceeding automatically under existing zoning. The county is reviewing data-center standards and locations, with completion anticipated in spring or summer 2027. These dates describe the county’s stated policy and schedule, which may change.
That review includes infrastructure questions such as electric transmission and distribution, substations, battery energy storage, and on-site generation. At the regional level, the Northern Virginia Regional Commission has identified energy reliability, greenhouse-gas reductions, battery storage, and possible reuse of residual heat as planning issues. Its page says a 2012 study found district-energy systems feasible under then-existing Virginia law and describes a 2024 map intended to explore the proximity of data centers to public facilities. This is a potential planning opportunity, not evidence of a regionwide heat-reuse system already in operation. The regional commission’s planning information describes this work.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What to know about generators, air quality, and noise
Loudoun County says most data centers have backup diesel generators that undergo mandatory testing for one hour once a week. Outside testing, the county associates generator operation with rare grid interruptions or direction from PJM during extreme demand. It also notes that diesel generators produce pollutants and that equipment and filtration practices vary by facility. The county’s environmental information describes these practices; they do not establish that every facility operates alike.
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The county says Virginia DEQ began mandating Tier 4-equivalent emissions standards for new or modified generators at data-center sites on July 1, 2026. It identifies DEQ as the authority for exterior air quality and points to a state monitoring project near Data Center Alley. For current requirements and implementation details, consult Virginia DEQ.
Noise can be another concern. Loudoun County notes that low-frequency and tonal sounds may be difficult to assess using ordinary A-weighted decibel measurements; some localities use octave-band or C-weighted measurements. The county says it is working on policy mechanisms to address these kinds of noise. Whether a particular site exceeds an applicable limit requires measurements and the relevant local rule.
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