I think it shakes out much more evenly if you count the westward expansion against Native American polities as imperialism. Don't forget taking part of Mexico, opening Japan and attempting to open Korea at gunpoint, engaging in 'unequal treaties' with China, annexing Puerto Rico and the Philippines, occupying Haiti, etc. And the whole Cold War we engaged in a similar level of hegemonic imperialism as the USSR did, even if we were more tolerant of democracies on 'our side'.

I love this stupid-ass country more than most (and more than I should honestly), and I go to bat for arguing against American Diabolism regularly, but we definitely have a long list of skeletons in our closets.

It engaged in a lot of imperialism, but then when it found itself on the top spot a new form of colonialism was being built, that of cultural and economic hegemony. Occupation by corporation rather than by military.

Korea, Japan, the UK, and the EU are essentially 100% dependent on the US, which is why the are kowtowing and letting Trump do whatever he wants. The US has always been imperialist, they just don't try to openly declare half a continent across the globe as rightfully theirs, just bullying their "allies" into favorable treaties