IMO, late 2009 / early 2010. The Citizen's United decision by SCOTUS, with a bit of a bump again by SCOTUS in 2013 when they basically nullified majority of the 1965 Voting Rights Act.

Congress is unarguably dysfunctional but (I believe) SCOTUS had a pretty large part in helping them get to where they are today...and in the difficulties involved with getting things back on track.

No, good point! I probably should have said getting things the way most American hope government would work. Or perhaps the way I think government should work, if I'm really being honest.

Based on my limited understanding of American politics, it depends on which side of the Mason–Dixon line you live on and when such a divided was relevant.