There's a reason why Toronto is the 4th largest city in North America, but only the 11th largest metro area.
By what measure do you get that statistic? Keep in mind that Statistics Canada's definition of a metropolitan area is more restrictive than the US Census Bureau's "Metropolitan Statistical Area". MSA's follow county lines, so by US definitions the Toronto MSA would include at least Toronto, York, Durham, Peel and Halton, whose combined 2011 census population is larger than the 2010 census population for all American MSA's except NYC, LA, Chicago and Dallas. And they often include a ring of intuitively rural-ish counties as well, so maybe more, and possibly enough to pass Dallas.
