The first census was conducted in the colony of New France in 1666 and regular census surveys were conducted by the French and then the British authorities right up to Confederation. The first national census after Confederation was conducted in 1871. From this date forward until 1951 the Census of Canada was conducted every 10 years. Starting in 1956 the Census was amended to a five year cycle. Some of these historical censuses are available from UBC Library in print, and others have been digitized and are available from Library and Archives Canada.
UBC Library has:
From the U of Toronto iSchool: a report locator for the Census of Canada, 1851-1951 containing bibliographical information for all Census publications for this period (drawn from the Historical Catalogue and other sources) along with links to open access digital copies where found (i.e. Internet Archive). The Report Locator is in .xls format. This spreadsheet contains a checklist of Census publications from 1851 to 1951 and provides link
Sources arranged in chronological order, from oldest to most recent:
Nominal or manuscript census returns consist of the original census forms, giving the occupation, place of birth, religion and other information about every resident of Canada. These documents are housed with the Library and Archives Canada. They can be released 92 years after the census.
Censuses - Historical The Library and Archives Canada website has searchable databases for the Census of 1851; the Census of Ontario 1871; the Census of Canada 1881; the Census of the Northwest Provinces 1906, and the Census of Canada for 1901 and 1911.
NOTE: in all cases, searching is only available by geography, not by individual family name.