Wisconsin
Data centers in Rock County, Wisconsin
The Census tracks 2 data center projects in Rock County, Wisconsin, with 800 MW of published capacity: 1 proposed, 1 cancelled.
How many data centers are in Rock County?
The Census tracks 2 major projects here as of Sep 22, 2026: 1 proposed, 1 cancelled. They are in Janesville, Beloit. The largest by published capacity is Viridian Data Center Campus (former GM/JATCO site) (800 MW).
Projects
| Project | Status | Capacity | Developer |
|---|---|---|---|
| Viridian Data Center Campus (former GM/JATCO site) Janesville, Rock County, WI | Cancelled | 800 MW | Viridian Partners (Viridian Acquisitions LLC) |
| Project Cornmaze Beloit, Rock County, WI | Proposed | — | Panattoni |
Recent changes
| Date | What changed | Project |
|---|---|---|
| Jun 22, 2026 | Panattoni holds an invite-only gathering on the project WIFR / Rockford News First | Project Cornmaze |
| Jun 2026 | Panattoni says the Town of Turtle board postponed a cost reimbursement agreement that had been set for its June 9 meeting DCD | Project Cornmaze |
| Jun 2026 | City Council votes not to extend the letter of intent with Viridian WMTV 15 News | Viridian Data Center Campus (former GM/JATCO site) |
| May 2026 | Panattoni informs local government it is taking over the project DCD | Project Cornmaze |
| Mar 5, 2026 | Pre-development agreement for Project Cornmaze becomes public DCD | Project Cornmaze |
| Feb 9, 2026 | City Council places a citizen initiative requiring voter approval for projects over $450 million at the GM/JATCO site on the Nov. 3, 2026 ballot Ballotpedia News | Viridian Data Center Campus (former GM/JATCO site) |
| Nov 2025 | Janesville City Council approves a letter of intent with Viridian 5-2 WPR | Viridian Data Center Campus (former GM/JATCO site) |
| Jul 15, 2025 | Town of Beloit signs pre-development agreement with Cambrin LLC WPR | Project Cornmaze |
| Jun 2024 | City of Janesville begins discussions with Viridian Partners on redeveloping the former GM site The Gazette (gazettextra.com) | Viridian Data Center Campus (former GM/JATCO site) |
Rock County data centers: common questions
How many data centers are in Rock County, Wisconsin?
The Census tracks 2 major data center projects in Rock County as of Sep 22, 2026: 1 proposed, 1 cancelled. That covers major sourced projects, not every smaller colocation or enterprise facility.
What is the biggest data center project in Rock County?
By published planned capacity, Viridian Data Center Campus (former GM/JATCO site) in Janesville, at 800 MW. Its status is cancelled.
This page collects the county-level record: every tracked project, moratorium and local rule we can source for Rock County. See all Wisconsin projects or look up projects near your ZIP code.
Cite this page
Last updated Sep 22, 2026. Figures may change as records are updated — include the date you retrieved them.
| APA | Data Center Census. (2026). Data centers in Rock County, Wisconsin. Retrieved from https://datacentercensus.com/us/wisconsin/rock-county |
|---|---|
| MLA | “Data centers in Rock County, Wisconsin.” Data Center Census, Sep 22, 2026, https://datacentercensus.com/us/wisconsin/rock-county. |
| Link | https://datacentercensus.com/us/wisconsin/rock-county |
Republishing a figure or table? Attribute it to Data Center Census with a link to this page. The underlying data is downloadable as JSON and CSV; the press kit has standing figures and contact details.