The Home District was called Nassau District from 1788 to 1792. It was originally bounded to the east by a line running north from the mouth of the Trent River and to the west by a line running north from Long Point on Lake Erie. The southern boundary was Lake Ontario and the northern boundary (probably not well surveyed at the time) was Lake Nipissing and the Nipissing River. The district town was originally Newark, later named Niagara-on-the-Lake, but it was moved in 1801 to the Town of York, later Toronto. The original counties making up the Home District were, from east to west, Northumberland, Durham, York, Lincoln, and Haldimand. Simcoe County was established from the northern part of York County in 1821. Other counties were also established as the later districts were formed.
The Home District's population increased at a much faster rate than the other districts and its administration was soon hard-pressed to carry out all its duties. As a result some of its land area was broken away to form new districts.
The formation of the new districts eventually left the Home District with only the County of York which, in 1838, stretched from the borders of Halton County in the west to those of Durham in the east. Further division came with the establishment of the counties of Ontario (to the east) and Peel (to the west). When the districts were dissolved in 1849, the three counties remained for a time the "United Counties of York, Ontario and Peel" but they had all formed independent administrations by 1866.
Maps of the Early Ontario Districts
The Archives of Ontario provides two Maps of the original Districts of Upper Canada as they were in 1788 before Upper Canada was created and three years later in 1791. Note that the only surveyed townships in 1788 were in Mecklenberg and Lunenburg Districts, but by 1791 there were surveyed townships all around the shore of Lake Ontario, and along the St Lawrence and the Ottawa Rivers.
A further series of maps illustrate the growth of the District system across the province.
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.