Cosponsorship Network Data

Developed by
James H. Fowler, Andrew Scott Waugh,
and Yunkyu Sohn

This page contains links to data on Cosponsorships in the U.S. Senate and U.S. House of Representatives for the 93rd to 108th Congresses. I have spent a lot of time developing this data so if you want to use it please cite the following two papers:

  1. Connecting the Congress: A Study of Cosponsorship Networks
    James H. Fowler
    Political Analysis 14 (4): 456-487 (Fall 2006)

  2. Legislative Cosponsorship Networks in the U.S. House and Senate
    James H. Fowler
    Social Networks 28 (4): 454-465 (October 2006)

These papers describe basic features of the data and how it was retrieved and processed. Because it is a very large data set there will inevitably be some mistakes in it. I do my best to continue improving the data--if you find mistakes please let me know and I will fix them.

Another extremely useful site for bill data is the Congressional Bills Project by E. Scott Adler and John Wilkerson.


Updated on 07/24/2017

GovTrack provided its own scrape of the Thomas data for many years, but they recently decided to deprecate this service. Here we provide a set of files for the 93rd to 114th Congress (1973 - 2016) that show all sponsorship, cosponsorship, and withdrawal decisions in their data.

Fields include the GovTrack version of the bill number, name of the sponsor/cosponsor, their bioguide id (if available in the GovTrack data), state, district, an indicator for whether the legislator was a sponsor (if false, then the person was a cosponsor), an indicator for whether the legislator was an original cosponsor, the date the sponsor/cosponsor signed on to the bill, and the date they withdrew (if they did).

A zipped copy of the GovTrack data is available here.

PLEASE NOTE: there are likely to be some discrepancies between their data and the data files below due to our errors, their errors, and errors in the Thomas data itself. We made no attempt to clean this data -- it is presented "as is" from GovTrack's own scrape of the Thomas data.


Updated on 09/22/2010

Andrew Scott Waugh and Yunkyu Sohn recently updated the cosponsorship data to include improvements from the Thomas database and data from the 110th Congress. A zipped copy of all new files is available here.

  • The and archives contain 4 column, comma-separated text files, with each row representing a bill, and columns containing the Congress number, bill type, bill number, and a dummy indicating if the bill was a private bill.

  • The and archives contain text files of identical length to house_bills.txt and senate_bills.txt. Each row contains a comma-separate vector of committee referrals for the corresponding bill.

  • The and archives contain comma-separated sponsorship/cosponsorship matrices for the 93rd-110th Congresses. Each row represents a Congressman, each column represents a bill. A value of 1 represents a sponsorship, while 2 represents a cosponsorship, 3 represent a cosponsorship after withdrawing the previous cosponsorship, and 5 represents a withdrawn cosponsorship.

  • The and archives contain comma-separated matrices of sponsorship/cosponsorship dates for the 93rd-110th Congresses. If Congressman i sponsored/cosponsored bill j, then datematrix[i,j] contains the date of that sponsorship/cosponsorship in a string.

  • The and archives contain 3 column, comma-separated, lists of Congressmen who served in the 93rd-110th Congresses corresponding to the rows in the cosponsorship matrices. The columns indicate the Congressman's name, Thomas ID#, and ICPSR ID#.

  • The and archives contain 4 column, comma-seaprated text files of bill status information, with each row corresponding to a bill in house_bills.txt or senate_bills.txt. These columns indicated whether the bill passed the House, passed the Senate, was agreed to in a conference, and signed/vetoed by the President.

  • Some of the bill html files at the Thomas database have incomplete information. The list of the incomplete html files is available here.


A zipped copy of all files used in the original two articles is available here. In these files an "NA" or a null value indicate the data is missing or was not matched. These occur because data was not available (e.g. early cosponsorship dates were not available at the time these files were generated) or there was a typo in Thomas or other problem with the matching procedure.

  • The SH.csv file is an aggregate results file. It is space delimited and here's a quick key:

    congress 93rd - 108th (i.e. 1973-2004)
    chamber House, Senate
    labels name
    ids ICPSR id
    ideol1 Poole and Rosenthal Common Space Score, 1st dim
    ideol2 Poole and Rosenthal Common Space Score, 2nd dim
    party 100=Dem 200=Rep
    seniority number of Congresses served
    sponsored number of bills sponsored
    pl number of sponsored bills that became law
    pb number of sponsored bills that passed chamber
    pa number of sponsored amendments that passed chamber
    inu unique inward cosponsors
    inb total inward cosponsor signatures
    inw total weighted inward cosponsor signatures (weights as described in my paper)
    outu unique outward cosponsors
    outb total outward cosponsor signatures
    outw total weighted outward cosponsor signatures
    between betweenness (unweighted)
    closeness closeness measure -- assumes bilateral ties
    evcent eigenvector centrality measure
    connectedness    connectedness measure
    cc individual clustering coefficient

The next files are all 283,994 element vectors with measures on each bill.

  • The bills.txt file is the name of each bill as identified in the Thomas database. The name identifies the type, chamber, Congress, and number of each bill. Here's a key:

    HC    House Concurrent Resolutions
    HE House Resolutions
    HJ House Joint Resolutions
    HR House Bills
    HZ House Amendments
    SC Senate Concurrent Resolutions
    SE Senate Resolutions
    SJ Senate Joint Resolutions
    SN Senate Bills
    SP Senate Amendments

  • The senate.csv file and house.csv are csv files that match ICPSR numbers ("id") to names ("name") and a few other variables for all congresses. ICPSR numbers are derived from and change if a person switches party, so it is important to match by congress.

  • The sponsors.txt file identifies the ICPSR code of each bill sponsor

  • The cosponsors.txt file identifies the ICPSR codes of each cosponsor (one bill per line, each cosponsor is space delimited) -- large (13M)

  • The cospcount.txt file is the total number of cosponsors on each bill

  • The dates.txt file is the date each bill was introduced

  • The cosponsordates.txt file shows the space delimited date(s) each bill was cosponsored -- the order of dates on each line conforms to the order of cosponsors on each line in the cosponsors.txt file -- large (22M)

  • The party.txt file shows the party of sponsor

  • The passedam.txt file shows whether amendment passed on the floor

  • The passedbills.txt file shows whether bill passed on the floor

  • The publaws.txt file shows whether bill became public law

  • The pvtbills.txt file shows whether bill is a "private" bill

This work by James H. Fowler, Andrew Scott Waugh, and Yunkyu Sohn is licensed under a
Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License