Why Democrats Can't Blame Gerrymandering

The Upshot's Nate Cohn has a nice item explaining why gerrymandering isn't responsible for Republican majorities in the House (for more on this argument, see an old John Sides post). Dave Weigel has a good response, arguing that yes, gerrymandering is the culprit. Who is correct? They both are! But Cohn is, on the whole, more correct.

Cohn’s case follows what most political scientists have been saying: For the most part, deliberately drawn district lines aren't the reason Democrats have received fewer seats in recent elections than the raw number of votes might indicate. Gerrymandering, by conventional measures, has cost Democrats only a handful of seats, not close to enough for them to have taken a House majority in 2012, when Democratic candidates received more total votes than Republicans. Instead, what’s hurting Democrats is “clumping” -- Democrats are increasingly rolling up huge margins in small geographic areas. The result is a few House districts with overwhelming Democratic majorities, which in the language of districting means “wasted” votes for Democrats (wasted, because in simple plurality elections anything more than a single vote win “wastes” votes for the winning candidate that could be used more efficiently in other districts).