Vital Statistics on Congress | Brookings Institution

"Vital Statistics on Congress, first published in 1980, long ago became the go-to source of impartial data on the United States Congress. Vital Statistics’ purpose is to collect and provide useful data on America’s first branch of government, including data on the composition of its membership, its formal procedure (such as the use of the filibuster), informal norms, party structure, and staff. With some chapters of data dating back nearly 100 years, Vital Statistics also documents how Congress has changed over time, illustrating, for example, the increasing polarization of Congress and the diversifying demographics of those who are elected to serve."