Pennsylvania in 2018: How Redistricting Does and Doesn’t Make a Difference

In this Field Note, we use precinct- and individual-level data on Pennsylvania to assess whether congressional redistricting influenced voter preferences in the 2018 midterm. Despite redistricting vastly altering the distribution of voters in House districts, this did little to change their preferences. Rather, redistricting contributed to Democratic House gains primarily by configuring a handful of districts to be more favorable to the Democratic Party. The evidence for minimal direct effects of redistricting on voter preferences, despite the presence of national political conditions breaking strongly in favor of Democrats, speaks to the increasing nationalization of American elections and with it, a concomitant decline in the incumbency advantage.