Skip to main content Accessibility help

Connecting the Congress: A Study of Cosponsorship Networks

  • James H. Fowler (a1)

Using large-scale network analysis I map the cosponsorship networks of all 280,000 pieces of legislation proposed in the U.S. House and Senate from 1973 to 2004. In these networks, a directional link can be drawn from each cosponsor of a piece of legislation to its sponsor. I use a number of statistics to describe these networks such as the quantity of legislation sponsored and cosponsored by each legislator, the number of legislators cosponsoring each piece of legislation, the total number of legislators who have cosponsored bills written by a given legislator, and network measures of closeness, betweenness, and eigenvector centrality. I then introduce a new measure I call “connectedness” which uses information about the frequency of cosponsorship and the number of cosponsors on each bill to make inferences about the social distance between legislators. Connectedness predicts which members will pass more amendments on the floor, a measure that is commonly used as a proxy for legislative influence. It also predicts roll call vote choice even after controlling for ideology and partisanship.

Corresponding author
Hide All

Author's note: I would like to thank Tracy Burkett, Diane Felmlee, Jeff Gill, Ben Highton, Bob Huckfeldt, Jonathan Kaplan, Mark Lubell, Mark Newman, Mason Porter, Brian Sala, and Walt Stone for helpful comments and Skyler Cranmer for research assistance. This paper was originally prepared for presentation at the 2005 Midwest Political Science Association and American Political Science Association annual conferences. A copy of the most recent version can be found at

Hide All
Beck, P. A., Dalton, R. J., Greene, S., and Huckfeldt, R. 2002. The social calculus of voting: Interpersonal, media, and organizational influences on presidential choices. American Political Science Review 96(1): 5773.
Bernard, H. R., Killworth, P. D., Evans, M. J., McCarty, C., and Shelley, G. A. 1988. Studying social relations cross-culturally. Ethnology 2: 155–79.
Birnbaum, Jeffrey H., and Balz, Dan. Case bringing new scrutiny to a system and a profession. Washington Post, January 4, 2006, 1.
Bonacich, P. 1972. Factoring and weighing approaches to clique identification. Journal of Mathematical Sociology 2: 113–20.
Burkett, Tracy. 1997. Cosponsorship in the United States Senate: A network analysis of Senate communication and leadership, 1973-1990. Ph.D. dissertation. Columbia, SC: Sociology, University of South Carolina.
Caldeira, Gregory A., Clark, John A., and Patterson, Samuel C. 1993. Political respect in the legislature. Legislative Studies Quarterly 18(3): 328.
Campbell, James E. 1982. Cosponsoring legislation in the U.S. Congress. Legislative Studies Quarterly 7(3): 415–22.
Cormen, T. H., Leiserson, C. E., Rivest, R. L., and Stein, C. 2001. Introduction to algorithms. 2nd ed. Cambridge, MA: MIT Press.
de Nooy, Wouter, Mrvar, Andrej, and Batagelj, Vladimir. 2005. Exploratory social network analysis with Pajek, structural analysis in the social sciences. New York: Cambridge University Press.
Ebel, H., Mielsch, L.-I., and Bornholdt, S. 2002. Scale-free topology of e-mail networks. Physical Review E 66(035103).
Fararo, T. J., and Sunshine, M. 1964. A study of a biased friendship network. Syracuse, NY: Syracuse University Press.
Faust, Katherine, and Skvoretz, John. 2002. Comparing networks across space and time, size and species. Sociological Methodology 32: 267–99.
Fowler, James H. 2005. Turnout in a small world. In The social logic of politics, ed. Zuckerman, A. Philadelphia, PA: Temple University.
Freeman, L. C. 1977. Set of measures of centrality based on betweenness. Sociometry 40(1): 3541.
Freeman, L. C., Borgatti, S. P., and White, D. R. 1991. Centrality in valued graphs—A measure of betweenness based on network flow. Social Networks 13(2): 141–54.
Galaskiewicz, J., and Marsden, P. V. 1978. Interorganizational resource networks: Formal patterns of overlap. Social Science Research 7: 89107.
Hall, Richard L. 1992. Measuring legislative influence. Legislative Studies Quarterly 17(2): 205–31.
Highton, B. 2000. Residential mobility, community mobility, and electoral participation. Political Behavior 22(2): 109–20.
Hindman, Matthew, Tsioutsiouliklisz, Kostas, and Johnson, Judy A. 2003. Googlearchy: How a few heavily-linked sites dominate politics on the web. Cambridge, MA.
Huckfeldt, R., Beck, P. A., Dalton, R. J., and Levine, J. 1995. Political environments, cohesive social-groups, and the communication of public-opinion. American Journal of Political Science 39(4): 1025–54.
Kessler, Daniel, and Krehbiel, Keih. 1996. Dynamics of cosponsorship. The American Political Science Review 90(3): 555–66.
Koger, Gregory. 2003. Position taking and cosponsorship in the U.S. House. Legislative Studies Quarterly 28(2): 225–46.
Krehbiel, Keith. 1995. Cosponsors and wafflers from A to Z. The American Journal of Political Science 39(4): 906–23.
Mariolis, P. 1975. Interlocking directorates and control of corporations: The theory of bank control. Social Science Quarterly 56: 425–39.
Mayhew, David R. 1974. Congress: The electoral connection, Yale studies in political science. Vol. 26. New Haven, CT: Yale University Press.
McGrory, Mary. 1995. Mccain, Gramm a strange pairing. Omaha World Herald, November 18, 1995, 17.
Moody, J. 2001. Race, school integration, and friendship segregation in America. American Journal of Sociology 107: 679716.
Newman, Mark E. J. 2001a. Scientific collaboration networks: I. Network construction and fundamental results. Physical Review E 64(016131).
Newman, Mark E. J. 2001b. Scientific collaboration networks: II. Shortest paths, weighted networks, and centrality. Physical Review E 64(016132).
Panning, William H. 1982. Blockmodels: From relations to configurations. American Journal of Political Science 26(3): 585608.
Pellegrini, P. A., and Grant, J. T. 1999. Policy coalitions in the US Congress: A spatial duration modeling approach. Geographical Analysis 31(1): 4566.
Polsby, Nelson W., and Schickler, Eric. 2002. Landmarks in the study of Congress since 1945. Annual Review of Political Science 5: 333–67.
Poole, K. T., and Rosenthal, H. 1985. A spatial model for legislative roll call analysis. American Journal of Political Science 29(2): 357–84.
Poole, K. T., and Rosenthal, H. 1991. Patterns of congressional voting. American Journal of Political Science 35(1): 228–78.
Poole, K. T., and Rosenthal, H. 1997. Congress: A political-economic history of roll call voting. New York: Oxford University Press.
Porter, Mason A., Mucha, Peter J., Newman, M. E. J., and Warmbrand, Casey M. 2005. A network analysis of committees in the U.S. House of Representatives. Proceedings of the National Academy of Sciences of the United States of America 102: 7057–62.
Proctor, C. H., and Loomis, C. P. 1951. Analysis of sociometric data. In Research methods in social relations, ed. Holland, P. W. and Leinhardt, S. New York: Dryden Press.
Rapoport, A., and Horvath, W. J. 1961. A study of a large sociogram. Behavioral Science 6: 279–91.
Rice, Stuart A. 1927. The identification of blocs in small political bodies. American Political Science Review 21(3): 619–27.
Rothenberg, R. B., Potterat, J. J., and Woodhouse, D. E. 1995. Choosing a centrality measure—Epidemiologic correlates in the Colorado-Springs study of social networks. Social Networks 17 (3-4): 273–97.
Sabidussi, G. 1966. The centrality index of a graph. Psychometrika 31: 581603.
Schiller, Wendy J. 1995. Senators and political entrepreneurs: Using bill sponsorship to shape legislative agendas. The American Journal of Political Science 39(1): 186203.
Sinclair, Barbara. 1989. The transformation of the U.S. Senate. Baltimore, MD: Johns Hopkins University.
Smith, Steven. 1989. Call to order. Washington, DC: Brookings Institution.
Straits, B. C. 1990. The social-context of voter turnout. Public Opinion Quarterly 54(1): 6473.
Talbert, J. C., and Potoski, M. 2002. Setting the legislative agenda: The dimensional structure of bill cosponsoring and floor voting. Journal of Politics 64(3): 864–91.
Truman, David. 1959. The congressional party: A case study. New York: Wiley.
Wawro, Gregory. 2001. Legislative entrepreneurship in the U.S. House of Representatives. Ann Arbor: University of Michigan.
Weingast, Barry. 1991. Fighting fire with fire: Amending activity and institutional change in the Postreform Congress. In The Postreform Congress, ed. Davidson, R. New York: St. Martin's Press.
Wilson, Rick K., and Young, Cheryl D. 1997. Cosponsorship in the United States Congress. Legislative Studies Quarterly 22(1): 2443.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Political Analysis
  • ISSN: 1047-1987
  • EISSN: 1476-4989
  • URL: /core/journals/political-analysis
Please enter your name
Please enter a valid email address
Who would you like to send this to? *
Type Description Title
Supplementary materials

Fowler supplementary material
Supplementary Material

 Unknown (6.8 MB)
6.8 MB


Altmetric attention score

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed