Not sure where to find an aggregate growing days figure, but there's clearly less of them per arable surface area in Canada compared to the USA.
Americans are not the self made men they made themselves believe to be. Played it well? Certainly. Starting with all the possible cards in your hand and geopolitical stability makes it very easy to do so.
or "How to say you know nothing about American history without saying you know nothing about American history"
Here's yale spending a semester on the revolution ( https://www.youtube.com/watch?v=shTBSGoYtK0&list=PLDA2BC5E78... ). Here's yale spending a semester on the civil war and reconstruction ( https://www.youtube.com/watch?v=QXXp1bHd6gI&list=PL5DD220D6A... ). If you took both in a year, you'd still only have the highlights of both events, covering about 40 years.
> The US has had zero real external threats post revolution
The US had external threats by Great Britain, Spain, Mexico, Barbary states, Native peoples, Japan, USSR, Italy, and Germany. They all took military and political action against the United States.
South american countries also have a fascinating history! But I'm not sure how that diminishes anything of the USA's struggle for existence. If anything, it heightens the fact that the founding of the USA is largely a miracle where the right people were in the right place at the right time. The fact that the USA's government has endured is by itself worth study.
and why limit it to external threats? are external threats the only one that threaten a country?