That's only half true. There were a lot of German, Scandinavian, Scot/Irish and Americans in the period too. The railway being completed and expanded and allowing the grain to be able reach foreign markets played a much bigger role than anything else.
The two biggest things to spur a Canadian development boom would be an earlier St. Lawrence canal and an earlier transcontinental railway. If you had the canal in the 1830s and the railway about 15 years earlier (doable, but expensive) you could probably double Canada's population by today.
I was trying to get a larger population by 1900, and was only expecting 1-2 million added by properly opening the Prairies.
I do still prefer our method of laying down the infrastructure and police services before opening it up though.