This erudite infographic from the webcomic mastermind behind xkcd, Randall Munroe, elucidates the history of the Senate and the House of Representatives from the nation's founding through the year 2012. Taking as a point of entry the number of members of congress who are left-leaning and right-leaning, the graphic traces historical trends that have shaped our politics over two centuries, from the original dispute between anti-administration factions who favored states' rights and the pro-administration coalition that promoted a central bank, to the advent of the tea party in response to the sweeping democratic win in 2008. A convenient legend explains the various colors and shapes that tell the story.