A Mystery That May Never Be Solved...

Looking at this chart, it's almost as if something happened in the mid-1960s that re-aligned Americans' party self-identification.

I wish there was some way to know what happened.

Republicans for Clinton

Update V: Former President George H. W. Bush (41) says he'll vote for Clinton. When the one-time national leader of your party plans to vote for the opposition (and also the wife of the candidate who unseated him), it might be time to give up the idea that Donald Trump is an ordinary candidate.

I don't recall anything like this in my lifetime.

https://www.washingtonpost.com/news/the-fix/wp/2016/06/30/heres-the-growing-list-of-big-name-republicans-supporting-hillary-clinton/

http://www.latimes.com/nation/politics/trailguide/la-na-trailguide-updates-meg-whitman-joins-chorus-of-republicans-1470224405-htmlstory.html

http://www.newyorkupstate.com/news/2016/08/rep_richard_hanna_we_should_all_be_done_with_donald_trump_commentary.html

https://goplifer.com/2016/07/22/resignation-letter/

http://www.cnn.com/2016/08/01/politics/sally-bradshaw-jeb-bush-donald-trump-florida/

http://www.usatoday.com/story/news/politics/onpolitics/2016/08/02/christie-trump-clinton-comella/87970914/

Update: not exactly coming out for Clinton, but this is a aggressive kneecap -
http://www.cnn.com/2016/08/08/politics/republican-national-security-letter-donald-trump-election-2016/index.html

And I believe Collins is only the second sitting US legislator to come out against Trump -
https://www.washingtonpost.com/opinions/gop-senator-why-i-cannot-support-trump/2016/08/08/821095be-5d7e-11e6-9d2f-b1a3564181a1_story.html

Update II: this is getting ridiculous. http://www.theatlantic.com/politics/archive/2016/08/republicans-who-support-hillary-clinton/494636/

Update III:

[conservative talk radio host Michael] Medved attended Yale Law School with Hillary and her future husband; while he didn't much care for Bill, he remembered her as "intensely likable." Indeed, he said, "to this day I don't know anyone, literally not anyone, who didn't like her, find her warm, sympathetic, a manifestly good person, a well-meaning person, not full of herself, not puffed up at all, down-to-earth, and a good friend . . . much nicer than what (her) critics think."

Emphasis mine. From http://www.nydailynews.com/opinion/joe-conason-republicans-love-hillary-clinton-article-1.2740094

Update IV: consolidated list from Vox.com: http://www.vox.com/2016/8/15/12444376/top-republicans-wont-support-donald-trump