I mean if you wanna dive that deep, it started when some religious extremists got kicked out of England for being too extremist (for the british empire!) and moved to the new world, killing the people who previously lived there.
… But up until 2008 shit more or less held together? Not pretending 'murica was ever good, but it was the 2008 recession that caused its structure, however fucky it had been from first principles, to really break down.