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.

Click here to access the Vital Statistics data tables »

Vital Statistics began as a joint effort undertaken by Thomas E. Mann of Brookings and Norman J. Ornstein of the American Enterprise Institute, in collaboration with Michael Malbin of the Campaign Finance Institute. The datasets were published in print until 2013 when the project migrated online for the first time. This year, Brookings’ Molly E. Reynolds spearheaded Vital Statistics’ most recent update. The eight chapters below contain more than 90 tables of data which were collected through the years of this project and updated most recently in October 2018. Whether you are new to Vital Statistics or an old Vital Statistics hand, here are a few things to know about the most recent update:

Each individual chapter and table is available for download below at no cost.

Each table is available in several formats, including—for the first time—as .csv files oriented in long, rather than wide, format. (The long format files do not contain the same source and methodological note information as the .xlsx and .pdf formats, so we strongly encourage you to download one other file format as well before using the data.)

contain the same source and methodological note information as the .xlsx and .pdf formats, so we encourage you to download one other file format as well before using the data.) As we’ve worked to update the data, we’ve made some changes to information from earlier years in order to correct coding errors and align methodology. A list of these changes are included in this document, and individual tables include a note indicating when earlier data was changed.

We encourage you to use these data in your own analyses and to send any questions or feedback you may have, by contacting vitalstatistics@brookings.edu.

Want to be informed about future updates to Vital Statistics? Sign up to receive email notifications about new data releases.

Acknowledgements

Vital Statistics is overseen by Molly Reynolds. Jackson Gode provided principal research support for the March 2019 updates with assistance from CJ Mayer, Cary Lynne Thigpen, Ananya Hariharan, and Rachel Orey; additional assistance on recent updates was provided by Curtlyn Kramer, Nick Zeppos, Danielle Bates, Natalie Smith, Claire Meczkowski, Emma Tatem, and Tanner Lockhead. Data collection for Chapter 3 was performed by Michael Malbin, Brendan Glavin, and the team at the Campaign Finance Institute. Work on all recent updates was informed considerably by the work of all past Vital Statistics authors and contributors, especially Thomas E. Mann, Norman J. Ornstein, Raffaela Wakeman, Andrew Rugg, and countless research assistants and interns at Brookings and AEI.