We were founded in genocide (1) and then our new nation institutionalized slavery. We didn’t do (much) colonialism, but we did practice a brutal mercantilism. Even after the Civil War, we allowed authoritarianism to persist in half the country. Our hands have never been entirely clean.

My own formulation in a text to a friend last night: 

You live in a fucking country that was acquitted by reason of insanity on a charge of matricide, that was erected on the backs of imported African slaves, that was reared on violence, nourished on (Jim) Crow and the "strange fruit" of lynchings. You think today's cruelty is "unamerican"???

(1) Genocide of Native Americans is a controversial topic among scholars. I disagree that the English settlers of North America committed genocide.