Interrupting with some facts for a moment...
https://xkcd.com/1127/"The New Deal wave consisted almost entirely of centrist Democrats. Over the course of the 20th century, these centrists generally lost ground to left and far-left Democrats--a slow-motion version of the process that has happened more rapidly and completely among House Republicans." DW-NOMINATE scores were used for this, by the way.
http://www.people-press.org/2014/06/12/political-polarization-in-the-american-public/"Republicans and Democrats are more divided along ideological lines – and partisan antipathy is deeper and more extensive – than at any point in the last two decades. These trends manifest themselves in myriad ways, both in politics and in everyday life. And a new survey of 10,000 adults nationwide finds that these divisions are greatest among those who are the most engaged and active in the political process."
http://www.people-press.org/2016/04/26/a-wider-ideological-gap-between-more-and-less-educated-adults/"Overall, 38% of the public expresses a mix of liberal and conservative positions. In both 1994 and 2004, nearly half (49%) had mixed attitudes. As our 2014 polarization study found, Republicans and Democrats increasingly are on opposite sides of the ideological spectrum."
http://www.people-press.org/topics/political-polarization/Lots more on that topic at that link if anyone is interested.
