The history of every U.S. House seat since 1870, in one chart

Close observers of chartmaking at The Fix (me, my mom) likely expected the chart that you'll see below. After all, we've already presented the partisan history of the Senate and the partisan history of gubernatorial seats. It was only natural, then, that eventually we'd get to the partisan history of the U.S. House of Representatives. And so we have.

As you might imagine, cobbling together the history of the House is significantly trickier than the 50 governors or the 100 senators. But let's look at the good stuff before we get to the mechanics.

Here are the states, in alphabetical order. The seats are in numeric order, with at-large representatives (either representing a whole state or elected after a Census) occupying the first row as needed. This reflects the change in party for the seat number, not the seat itself if it was renumbered.