Regional Municipalities
- Durham Region
- Halton Region
- Muskoka District
- Niagara Region
- Peel Region
- Waterloo Region
- York Region
Counties
- Brant County
- Bruce County
- Dufferin County
- Elgin County
- Essex County
- Frontenac County
- Grey County
- Haldimand County
- Haliburton County
- Hastings County
- Huron County
- Lambton County
- Lanark County
- Leeds and Grenville
- Lennox and Addington
- Middlesex County
- Northumberland County
- Oxford County
- Perth County
- Peterborough County
- Prescott and Russell
- Prince Edward County
- Renfrew County
- Simcoe County
- Stormont, Dundas and Glengarry
- Wellington County
Districts (Northern Ontario)
- Algoma District
- Cochrane District
- Kenora District
- Manitoulin District
- Nipissing District
- Parry Sound District
- Rainy River District
- Sudbury District
- Thunder Bay District
- Timiskaming District
Single-Tier Municipalities
- Barrie
- Brantford
- Greater Sudbury
- Guelph
- Hamilton
- Kawartha Lakes
- Kingston
- London
- Ottawa
- Peterborough
- St. Thomas
- Thunder Bay
- Toronto
- Windsor
- Chatham-Kent
- Norfolk County
Understanding Ontario's County System
Ontario's upper-tier municipal structure includes three types of jurisdictions:
Regional Municipalities
Regions were created in the 1970s to manage urban growth areas. They provide region-wide services like public health, waste management, and regional planning while lower-tier cities and towns handle local services.
Counties
Traditional county governments primarily in rural and small-town Ontario. Counties coordinate services among multiple townships and municipalities while preserving local autonomy.
Districts
Found in Northern Ontario where population density is low. Districts provide minimal coordination with most services delivered at the local level or directly by the province.
Single-Tier Municipalities
Major cities that operate independently, providing both regional and local services. These include Ontario's largest cities and some specialized rural municipalities.