Since 1948, ANES has conducted surveys, usually administered as in-person interviews, during most years of national elections. This series of studies, known as the ANES "time series," constitutes a pre-election interview and a post-election interview during years of Presidential elections, and, usually, a post-election interview only during years of midterm elections.

Data compiled by MIT professor Charles Stewart III.

This public resource provides data and information about more than 400,000 bills introduced in the U.S. Congress, currently 1947-2008, along with extensive information about each bill's progress and sponsor.

Historic and current data on voting and elections in the U.S. Includes analyses of voting behavior, election processes, and voter demographics.

Detailed data on campaign contributions and expenditures by candidates, parties, and committees.

Tracks pre-election polls.

Data sets for US politics: campaign finance, lobbying, 527s, and candidate's personal finances.

Comparative data on policy trends based on bills, hearings, laws and votes.

Research papers and congressional data generated by Howard Rosenthal and Keith Poole.

Jeff Lewis and Keith Poole's up-to-the-minute roll call voting data from the US Senate and US House. Data culled from the Senate and House Clerk's webpages.