European settlement began in earnest in the 1830s and brothers Lieutenant-Colonel Robert Campbell and Major Robert Campbell were granted on the Trent River in 1831. A settlement grew, and in 1876, the Village of Campbellford was separated from Seymour and incorporated as a separate municipality.
Seymour was originally part of the United Counties of Northumberland and Durham, then Northumberland after the United Counties were restructured in 1974. In 2001, Seymour was amalgamated with Campbellford, the Village of Hastings and Percy Township to form the Town of Campbellford / Seymour, Percy & Hastings. It was renamed Trent Hills later that year. According to the 2001 Census, Seymour had a population of 4,528 at the time of amalgamation.
The Archives of Ontario supply a map of the county dated between 1945 and 1951 which shows the old townships and their placement geographically.
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 Northumberland County