| Ontario | |
|---|---|
| County Number | 52 |
| Postal abbr. | ON |
| Capital | Toronto |
| Nickname | Yours to Discover, The Heartland Province |
| ISO | CA-ON |
| FIPS | CA08 |
| Name | County | Postal Code |
|---|---|---|
| Ridgeway | 3526 | L0S |
| Thamesford | 3532 | N0M |
| Plainfield | 3512 | K0K |
| Hammond | 3502 | K0A |
| Essex | 3537 | N0R N8M |
| Seguin | 3549 | P2A |
| Joyceville | 3510 | K0H |
| Alberton | 3559 | L0R |
| Wardsville | 3539 | N0L |
| London | 3539 | N5V N5W N5X N5Y N5Z N6A N6B N6C N6E N6G N6H N6J N6K N6L N6M N6N N6P |
| Name | State |
|---|---|
| Haliburton | Ontario |
| Northumberland | Ontario |
| Peterborough | Ontario |
| Dufferin | Ontario |
| York | Ontario |
| Prince Edward | Ontario |
| Kawartha Lakes | Ontario |
| Thunder Bay | Ontario |
| Huron | Ontario |
| Ottawa | Ontario |
| Peel | Ontario |
| Halton | Ontario |
| Kenora | Ontario |
| Frontenac | Ontario |
| Cochrane | Ontario |
| Niagara | Ontario |
| Waterloo | Ontario |
| Hastings | Ontario |
| Parry Sound | Ontario |
| Perth | Ontario |