These two graphs from CIRCLE tell the story of youth in the 2018 election.
First, turnout rose dramatically. The blue line shows estimates of youth turnout using the only method that’s available immediately after an election. CIRCLE relies on the exit polls plus the number of ballots cast and demographic data to generate that line. As shown, this estimate has tracked a different method (the Census Bureau’s November surveys, which simply ask people whether they voted) pretty well historically. As CIRCLE acknowledges, their method could lead to errors if the exit polls’ age breakdown is wrong; but it’s the best available method, and it suggests a very strong year for youth.
Second, although young people do not always vote Democratic, they sure did this year. The partisan gap is unprecedented. I happen to think it’s folklore that once people have voted the same way three times, they keep voting that way for life. However, folklore sticks for a reason, and it’s certainly plausible that voting for the same party a few times in a row creates a habit that tends to persist. If that’s true, Republicans are taking a chance on long-term catastrophic damage.
Meanwhile, if you’re a Democrat in a mood to be a little chagrined by yesterday because your high expectations were not quite met (after all, you are a Democrat), just don’t blame youth. These trends are startlingly positive for Democrats. The problem lies further up the age pyramid.