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The 1851 census, actually taken in January 1852, is sometimes considered the first complete one of Canada. There were prior censuses that covered smaller areas where usually only the heads of household were named.
Not all the census returns now exists, if they ever did. There were likely no go zones. In previous attempts some of the residents of Lower Canada (Quebec) were so suspicious that the results would be used for tax purposes that enumerators feared for their lives in approaching a community with a book and pencil in hand -- this from the Toronto Globe in its 10 January 1852 edition.