So first...I really wanted to know where democrats actually gained votes. This is a slightly different question from 'which demographics shifted towards democrats?' For example...if democrats gained 5% more males and males are 50% of the population, that's a bigger gain for than gaining 10% more Asian voters if Asians are only 5% of the population.

To understand the plot below, think of it like the following. If you have 100 voters, 50% of them are female, and 60% of females voted for democrats, then 30 (50%*60%) voters were female and voted for democrats. The plot below calculated this for 2014 and 2018, and is sorted by largest gain from left to right:


The way to read that then is that democrats gained the most new votes from females, college graduates, and voters with no religion. This isn't a perfect metric, but I like that it combines both the size of a demographic and how they shifted between 2014 and 2018.

With that out of the way, here is a tool for doing detailed comparisons between the exit polls in 2014 and 2018...

Exit poll analysis tool