About the project

Voteview allows users to view every congressional roll call vote in American history on a map of the United States and on a liberal-conservative ideological map including information about the ideological positions of voting Senators and Representatives. The original Voteview of DOS was developed by Keith T. Poole and Howard Rosenthal at Carnegie-Mellon University between 1989 and 1992. Poole and Rosenthal developed Voteview for Windows in 1993 at Princeton University and that work was continued by Boris Shor. The legacy version of the website is available at legacy.voteview.com.

The new voteview.com combines the visualizations provided by the now obsolete Voteview desktop system, data and NOMINATE estimates provided by the old voteview.com web site, and up-to-date voting data from the current Congress with new search, download and visualization functionality.

Ideological positions are calculated using the DW-NOMINATE (Dynamic Weighted NOMINAl Three-step Estimation). This procedure was developed by Poole and Rosenthal in the 1980s and is a "scaling procedure", representing legislators on a spatial map. In this sense, a spatial map is much like a road map--the closeness of two legislators on the map shows how similar their voting records are. Using this measure of distance, DW-NOMINATE is able to recover the "dimensions" that inform congressional voting behavior.

The primary dimension through most of American history has been "liberal" vs. "conservative" (also referred to as "left" vs. "right"). A second dimension picks up differences within the major political parties over slavery, currency, nativism, civil rights, and lifestyle issues during periods of American history.

The technical details of the DW-NOMINATE model can be found in Poole's Spatial Models of Parliamentary Voting. Poole and Rosenthal's Ideology and Congress explores the nature of voting in Congress and the political history of the United States through the lens of the ideological dimensions recovered by DW-NOMINATE and is a useful companion to this site.

UCLA's Department of Political Science and Social Science Computing host and maintain NOMINATE score data and voteview. We welcome feedback, questions, and media enquiries concerning this project.


This project was made possibe by support from The William and Flora Hewlett Foundation (Grant #2016-3870), the National Science Foundation (NSF-SBS-0611974), UCLA Social Science Computing and the University of Georgia.

Project Staff

  • Project Lead:

    Jeffrey B. Lewis
    Professor, University of California Los Angeles

  • Directors Emeritus:

    Keith T. Poole
    Philip H. Alston, Jr. Distinguished Professor, University of Georgia
    Professor Emeritus, University of California San Diego

    Howard Rosenthal
    Professor of Politics, New York University
    Roger Williams Straus Professor of Social Sciences, Emeritus, Princeton University.

  • Lead Database Developer, Voteview.com: Adam Boche, University of California Los Angeles
  • Lead Developer, Voteview.com: Aaron Rudkin, University of California Los Angeles
  • Lead Developer: Luke Sonnet, University of California Los Angeles
  • Past Contributors: Erik Hanson, Felipe Nunes, Fabio Souto

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Licence and Code

VoteView code available on GitHub:

VoteView data:

Some graphics used under license:

External code libraries: