538: The Congressional Map Has A Record-Setting Bias Against Democrats

[Anna Komnene]

The gerrymanders are not even the main cause - reasonable maps in Ohio, North Carolina, Michigan, Pennsylvania, and Wisconsin would combined swing MAYBE 6-7 seats, but probably less.

Dems' problem is a simple one: their voters self-pack. The constitution places a large value on geographic diversity and winning individual states, and on both measures Dems fail miserably.

Remarkably lazy analysis by 538 honestly.

I'm curious to see how you apply your theory to the House in the 2006 and 2008 elections.

[Anna Komnene]

Another thing to keep in mind is that hostile maps also discourage credible candidates from running, which in turn decreases the willingness of the opposition party to spend resources in those districts. Kind of a double whammy that makes things even more difficult for the people who do have the courage to run. Just a little meaningless anecdote, but I got the chance to have dinner with a retired congressperson from New York a while ago, and they basically told me that everyone is constantly paranoid about being drawn out of their districts and are willing to do all sorts of things ranging from innocent to extremely shady in order to prevent that from happening. Lovely thing, politics is.