How do we know that higher turnout benefits Democrats?

Preliminary thoughts on a new book that claims it doesn’t

On Twitter this week Matt Grossman linked to a new book called “The Turnout Myth” in which the authors political scientists Daron Shaw (a former professor of mine) and John Petrocik suggest that the usual claim that higher turnout benefits Democrats is wrong. Grossman tweeted out the following graph as a central finding of the book. In congressional ele…