Analysis of All Swing House Seats

Nate Silver started 538.com four years ago to cover the presidential race to do what no other poll was doing, predict the electoral college vote which matters a whole lot more than any national poll.  Well, now he does House, Senate and a ton other other races.  Here, for example is his current analysis on the House of Representatives.  He has the Republicans with a solid 230 and the Dems coming in at 180.  Now this number will change between now and November as Silver aggregates polls and weighs them depending on their size and accuracy in the past.  This leads to a nice discussion of what it is about our electoral make-up that the overwhelming majority of House seats rarely change (incumbent advantage say political scientists, rather than gerrymandering).