Community structure in the United States House of Representatives

We investigate the networks of committee and subcommittee assignments in the United States House of Representatives from the 101st-108th Congresses, with the committees connected by interlocks or common membership. We examine the community structure in these networks using several methods, revealing strong links between certain committees as well as an intrinsic hierarchical structure in the House as a whole. We identify structural changes, including additional hierarchical levels and higher modularity, resulting from the 1994 election, in which the Republican party earned majority status in the House for the first time in more than 40 years. We also combine our network approach with the analysis of roll call votes using singular value decomposition to uncover correlations between the political and organizational structure of House committees. (c) 2007 Elsevier B.V. All rights reserved.