This was a question I asked my grade 7 history teacher and he was never able to give me a great answer. I understand there is more habitable space in the US, but there are a number of geographically smaller countries than Canada with a much larger population.
hi! you'll find some responses here, plus links to a few other related posts
I do not know a ton about Canada, but from what I understand based on their climate they were never a heavily agrarian society. While America had plenty of fertile soil, so in the beginning we were heavily agrarian. The next best source of free labor to work farms besides slaves, is children. Thus in the beginning children were a path to prosperity and wealth for Americans and in fact any agrarian society.