CENSUS
There are very early census records  in Lower Canada (Quebec) that reach back to the 1600s. The first official Canadian census was in 1790. However,  most researchers of Ontario  records find it easier to begin by looking at the microfilmed records held by The Archives of Ontario in Toronto. .
Census in Canada was  taken every ten years:  1842, 1851, (actually 1852), 1861, 1871, 1881, 1891, and 1901.  These records are preserved on microfilm, which may be inter-loaned to any Public Library with a microfilm reader, or to a LDS Family History Centre (The Church of Latter Day Saints). No, this group does not try to convert you, but rather makes their Family History Centres open to the public across North America.  I have found them very helpful.
Gratefully, many census records are now in
print form and indexed, and several websites offer Canadian census records. 
The Archives of Canada in Ottawa has  recently put the 1901 census for most of Canada on-line at their web site.
However these are the actual microfilmed pages, and they are not easy to read. Subsequently, I will include some 1901 census records on this website for Gillespie families in Ontario at that time.

"Ontario Gillespie Census Records" is the third publication in a series of references volumes  produced by this office.  The records provided on the following pages are from that volume. An actual printed record for each reference is held on file in our office.
The volume is indexed, enabling one to look at many family names besides Gillespie, and to track people with the same first name, all across the Province.
CENSUS LINKS:
Gramma's Corner
National Archives of Canada
Ontario Genealogical Society

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