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Do we have the Demographic and population details?
going to guess that 90% of the population lives below that line.
My guess would be closer to 98%. Almost no one lives up there.
It looks like the boundary between the temperate, agricultural zone and the boreal zone.
There are more people living in Southern Canada than Northern Canada as far as the population goes. Beautiful country, but too cold in the winter for me. The further north you go, the shorter the summer.
I know that as of 10 years ago, 80% of the population lived within 100km of the US Border.