that's because the US wiped out the previous inhabitants of North America
if that hadn't happened you'd likely be facing the same situation, i.e. having 30 neighbours instead of 2
if that hadn't happened you'd likely be facing the same situation, i.e. having 30 neighbours instead of 2
it's quite significantly larger
now, imagine if today that 80% wasn't part of the US, and was instead controlled by the indigenous population (likely tens of sovereign states)
would there have been large scale wars in the 19th and 20th century? it's quite obvious the answer would have been "yes"
See: the Trail of Tears, the actual, literal death march of natives out of their ancestrial lands because "manifest destiny"