I've touted the Catalist estimates that have been released so far as the best estimates we have of voter turnout and preferences by demographic group for the 2018 election and previous elections--and therefore the best tool for helping us understand what really drove the 2018 election results.
So send up the balloons! Yair Ghitza and the good folks at Catalist have just released their final data for 2018, incorporating final precinct-level elections and, critically, individual-level vote history records from voter files around the country. These are some tasty data and as close as we are ever likely to get to a definitive portrait of the 2018 election.
The entire article is up on Medium, with plenty of interesting tables,charts and maps. I urge you to check it out. But here are some items that struck me as particularly important given the post-election strategy debates that have unfolded. .
1. Relative to 2016, the shift toward the Democrats was larger in rural than in suburban areas. This was true among white voters as well.
2. There were big pro-Democratic shifts among both white college (+10) and white noncollege (+7) voters.
3. Turnout was outstanding and the demographic composition of the electorate came remarkably close to that of a Presidential election year. This was due to fewer Presidential dropoff voters and more midterm surge voters.
4. Despite the stellar turnout performance, the overwhelming majority of the Democrats' improved performance came not from less Presidential dropoff and more midterm surge but rather from voters who voted in both elections and switched their votes from Republican in 2016 to Democratic in 2018. When I say "overwhelming" I mean it: Catalist estimates that 89 percent of the Democrats' improved performance came from persuasion--from vote-switchers--not turnout. That's important.
These data imply that 2020 could well be another high turnout election. That should be helpful for the Democrats, who will not and should not stint in their efforts voter mobilization. But the critical role of persuasion will remain, most especially in ensuring that 2018's vote-switchers don't switch back.