Since 1998 Cornwall Township has been part of the municipality of South Stormont.
Cornwall and Osnabruck were two of the original eight "Royal Townships" established along the Saint Lawrence River in Upper Canada. Osnabruck was named after a title formerly held by Prince Frederick, son of George III, who at one time was Prince-Bishop of Osnabrück in Lower Saxony, and Cornwall was named for Prince Frederick's title as Duke of Cornwall.
The Lost Villages, ten ghost towns which were flooded by the construction of the Saint Lawrence Seaway in 1958, were located in the former Cornwall and Osnabruck Townships. The communities of Long Sault and Ingleside were newly built to accommodate displaced residents of the flooded villages. Due to this relocation, the towns were entirely planned from their inception - a rarity in Ontario. Several streets in the two communities are named for the flooded settlements.
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 1914 are now available [October 2012]; 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. All of the original census (1851-1911) images are online with the exception of that for 1861. Not all of them are indexed. Later censuses are not yet available. Census divisions were redrawn as the population increased and more land was inhabited.
E-books and Books
Some websites with more local information on Stormont County