This section contains .csv files that provide descriptive data as well as ideological data for congressional rollcalls, individual member votes, members of congress, and parties. You can find information such the descriptions of rollcalls, what proportion of voting members were correctly classified by the ideological cutting line for that rollcall, the ideological position of members of congress, and more.
Both the rollcall data and the data on members are split into chambers and congresses, although you can select some combinations of the two to download. The data on parties is a dataset with some metadata about all of the different parties as well as their average ideological position and membership size broken down by congress and chamber.
You can see the about page for more information about NOMINATE. For information about specific data fields in the database, see the members data dictionary and rollcalls data dictionary. Note: Each legislator is assigned a single estimate for their entire career (excluding certain party switches). Dynamic estimates may be made available in the future.
Complete database (approx. 500MB zipped).
Our database is available in MongoDB bson/json format. This release is updated weekly.
Browse prior database releases
We retain a year worth of archival data online. Archival releases may be missing new rollcall or member data, and may also be missing corrections made to existing data.