Lets say that Canada gets the British and French Caribbean and the US is somewhat less immigrant friendly (and Canada a lot more immigrant friendly), what do you think the maximum population Canada could reach by 1970 is? The USA went from about 5 million to 40 million from 1800 to 1870, so could Canada go from about 5 million to 50 million due to modern transport technology? 60 million? Or is the cold more of an issue, making 30 million a more likely target?