Over at Enik Rising, Seth Masket posts a great video documenting the spatial location of California state legislators through the past century or so. If you’re not too distracted by the accompanying soundtrack, all kinds of interesting things are visible: the rise of the Progressives, the Democratic tide of 1932, and (to my eye at least) the growing polarization between Democrats and Republicans in the past 20 or so years.
(See also Seth’s post on whether the Democratic Party helps the poor.)