Ontario County was a former county of Ontario, Canada. The area began to be settled before 1800, but it was not an administrative entity until 1852. Its proximity to Toronto and the richness of its farmland has continuously made it a popular place to live through the past two centuries.
During the 1970s the Province of Ontario began an undertaking to reorganize its administrative structure. One of the highlights of the changes was to remove the County of Ontario from the map and combine the better part of it with its eastern neighbour, Durham County, under the name The Regional Municipality of Durham, commonly known as Durham Region.
Prior to 1853 Ontario County was part of York County within the Home District of Upper Canada or Canada West. It was established in 1849 as a section of York County but was not made into a county separate from York until 1853. However, its initial settlement, mostly by United Empire Loyalists, started before 1800.
In historical documents many places will be described as being in the County of Ontario. Entries before 1850 will refer to them being in the Home District. However, on present-day maps and gazetteers, these places will be within the boundaries of Durham Region.
For reference, there follows a list of new municipalities formed within Durham Region in 1974 together with their equivalents in the former Ontario County.
A sketchmap from Ontario GenWeb gives a more visible outline of the townships.
The map of Ontario County circa 1951 from Ontario Archives locates the communities and physical features of the county. (Click at the bottom of the page to see the map enlarged.)
The primary source for basic documents (vital statistics, land records, wills) for people who lived in the Province of Ontario is the Archives of Ontario, 134 Ian Macdonald Blvd, Toronto, Ontario, Canada M7A 2C5.
Civil registration did not begin in the province until 1869. Before then there may be church records of baptisms and burials. For the most part these are still held by the denomination who recorded them. Copies of marriage records made pre-1869 had to be sent by individual clergymen to the registrar of the county in which the marriage took place. These marriage records are available through Ontario Archives, on micorfilm through LDS libraries, and on paid and unpaid websites, but because they were copied at the registrars' offices, they cannot be considered a primary source.
Vital Records after 1869
Birth, marriage and death registrations are not open to the public until a specific number of years after the event occurred. Births to 1915 are now available [October 2014]; dates for marriages and deaths are later. Birth and death registration was not universally carried out in the early years after its adoption. Deaths were more apt to be reported than births for several years. The more rural the area, the less likely it would be that these happenings were reported to the authorities.
Land Records and Wills
Information on how to access land records and wills is best sought on the Archives of Ontario website. An ancestor's land holding might be found on Canadian County Atlas Digital Project if he was in occupancy circa 1878.
Association for the Preservation of Ontario Land Registry Office Documents (APOLROD). A list of Land Registry Offices for all Counties of Ontario.
The original censuses are in the hands of Library and Archives Canada, known to Canadians as "LAC". Copies of original microfilms are online at the LAC website for all censuses up to 1911. Each census database is preceded with an explanation of the geographical area covered, the amount of material retained (some census division material has been lost), the questions on the census form, and whether there is a name index. Census divisions were redrawn as the population increased and more land was inhabited. The 1921 census is only available through Ancestry.ca, but it is free-to-view.
E-books and Books
Some websites with more local information on Ontario County