Last week, I shared the news that we at Catalist have developed a new methodology for projecting the true shape of an electorate, almost immediately following Election Day. We followed it up on Friday with estimates of the composition of the electorate, going back to 2006.

Today, we’re releasing round 2 of our results: what were the voting preferences of each group? In other words, who did they vote for? Like the last post, we’re going to focus on the national Congressional election[1], and we will be leveraging a large-scale poll conducted by YouGov, which we combine with our large-scale voter registration database. We’ll also refer back to the changes in turnout/composition described last week, to provide a fuller picture of each of the relevant groups discussed below.

As a refresher, or if you’re curious, you can read more about our new methodology in our initial post. In short, we spent the last week combining all of the information available — pre-election projections, early voting, county and congressional district election results, precinct results where we have it available , and polling data — to come up with our estimates. All of this builds on academic work, which we developed in collaboration with Andrew Gelman — the most relevant academic paper is here. A few more methodological notes are at the end of the post, for those who care about the details.

For the groups discussed below, we’re showing the share of voters (adding up to 100%) and Democratic candidate margins (+10 means the Democrat won by 10 points) for 2014, 2016, and 2018. We also show a few graphs describing how these have shifted over time. There is too much data to show everything at once, so we made a few choices as to what were the most obvious and relevant data points. In the graphs, we show how the share of voters shifted from 2014, the last midterm, because there are long-term structural differences between midterm and presidential turnout. For change in Democratic margin, we instead show a comparison to 2016, which we think is a better baseline for understanding vote margins. Lastly, we use Presidential margins in Presidential election years and national Congressional margins in midterm years, because these are often considered the primary national elections for each of those years.

If you would like to see data for more comparisons and more groups, the detailed data is here.

For all of these, the numbers are rounded, so they may not add up to 100%.

1. Young voters surged in both turnout and Democratic support levels.

There was an increase in youth turnout (18-29) between 2014 and 2018, from 8 to 9% of votes cast[2]. Just as importantly, Democratic vote margins increased substantially since 2016, going from +25 to +44 Democratic. This is especially true among young white voters. In 2016 (and 2014), Democrats and Republicans were essentially tied. In 2018, there was a huge shift and Democrats won them by 26 points. There was also a large shift among 30-44 year olds, who showed a 2-point boost in share, and a 13-point shift in Democratic margin. Again this was bigger among white 30-44 year olds, who voted for Republicans by 21 points in 2014 and 9 points in 2016; they supported Democrats by 9 points this year.