The Colbourne District was formed from the Newcastle District in 1838. The Newcastle District was cut in half by this move. Colbourne took the northern half, the county of Peterborough; Newcastle retained Durham and Northumberland to the south. The counties of Peterborough and Durham were much larger in 1838 than they were later, following the abolition of the District system and the expansion of population into lands not facing directly onto the Great Lakes.
The Archives of Ontario has produced a series of maps illustrating the growth of the District system across the province. Each map ought to be expanded to its maximum size in order to benefit from the information it contains. Return to the collection using the "back" button on your browser.
Ontario Districts: an Explanation
When Upper Canada was formed in 1788 it was immediately divided into four districts: Hesse, Nassau, Mecklenburg and Lunenburg. In 1792 these names were changed to Western, Home, Midland and Eastern respectively. The expansion in population of the province, and in the area settled, obliged the number of Districts to increase. By 1849 there were twenty individual districts, each with a number of counties under its jurisdiction.