Stranger in My Own Land

I am perplexed (as, apparently, many progressives are):
Social Security is the most effective and popuplar social program in US history; State after state has done what the Federal government won't~increase minimum wage; Marijuana is now legal in a handful of states; Marriage equality is now a reality in 3/5 of the country (often thanks to GOP appointed judges!); AND the people who have demanded, accepted, and celebrated Social Security, Minimum Wage hikes, legalized pot, and Marriage equality voted for Reps, Senators, and Governors who oppose ALL OF THAT. Some sociologist can become famous if s/he will figure out why centrist people either vote for (or don't vote at all) right wing ideologues who oppose what they actually value. Of course gerrymandering, the assault on the Voting Rights Acts, and Citizens United have made it difficult for marginalized people to have a voice in government, but even with those obstacles, I still can't make sense of a nation that twice consecutively votes for a progressive president also voting consistently (or not at all) for legislators who work tirelessly to oppose that president's vision. I am a stranger in my own land.