Mississauga freezes data centres above 10 megawatts for a year, and three American councils reach for the same tool in the same week

On 16 September 2026 Mississauga City Council approved an Interim Control By-law that stops new major digital infrastructure development, data centres above all, anywhere in the city. The threshold is a total peak power demand of 10 megawatts or more. The city's own announcement describes the pause as lasting up to one year while staff conduct a comprehensive review of the sector and assess whether the Official Plan and the Zoning By-law need updating, with reference to Ontario's Data Centre Playbook.

An Interim Control By-law is not a rejection. It is a provincial planning instrument that lets a municipality freeze a defined type of development in a defined area while it works out what rules should apply. The city describes it in exactly those terms. Several outlets covering the vote report that the freeze can run for one year and then be extended to two; the city's release refers only to one year, and for anyone holding a site the difference is not trivial.

The vote was unanimous. Reporting on the council meeting says the by-law captures a proposed 40 megawatt Prologis facility in the Meadowvale Business Park, which is now in limbo, and that the company said it was considering its next steps. Council had signalled the move in late July, when it directed staff towards a pause; September is when the instrument actually took effect.

Mississauga is not alone, and that is the part worth watching. In Elgin, Illinois, the city council gave unanimous preliminary approval to a one-year data centre moratorium on 15 September, despite having received no data centre applications at all. The Troy planning commission approved a moratorium extension on 17 September. The Town of Normal, Illinois votes on 21 September on extending its own moratorium on accepting data centre permits through May 2027; town staff told councillors in a memo that renewed state-level interest in data centre regulation, including the stalled POWER Act, means any state action will shape how the town handles applications.

Why this belongs in a register of decentralisation: the argument for hyperscale compute is that it is a national, even civilisational, necessity, and that the planning question is a local formality. An interim control by-law is the local formality declining to be one. It relocates a decision about where electricity, water and land get committed from a provincial playbook and a corporate siting team to a council chamber, and it does so with an ordinary planning tool that every Ontario municipality already has on the shelf. In the same week, three American municipalities reached for the equivalent. That is not a movement. It is a procedure being discovered, which tends to spread faster.

The honest caveat is that a pause is not a policy. Mississauga has bought itself a year to write rules it has not written. What emerges could be a hard standard on power, water, noise and setbacks, or it could be a zoning amendment that waves the same projects through with a landscaping condition attached. The measure of this story in a year is the by-law that replaces the by-law.