Where did 20 million democrat votes go?

They did what -- unfortunately-- Americans tend to do: when forced with two major candidates, neither of which enthuses them, they sit on their hands and don't vote. Rather than voting for a third party or fourth party candidate, which may be futile but will send a louder message to the politicians than just not voting. Brett Stephens of the NY Times had a great column on political ideologues' inability to assess their failures to hear the voters vs. looking for tactical campaign errors to blame.