sunfoundation:

US Senate Agreement Groups: How US Senators Have Agreed over Time

The interactive flow graph Agreement Groups in the United States Senate [friggeri.net] by French PhD student Adrien Friggeri reveals how US senators have agreed (or disagreed) over time.

All historical US Senators were subdivided in overlapping groups of agreement using a custom-made community detection algorithm called C3, which was specifically designed to detect maximally cohesive groups in a network. Here, I guess the network was created from recognizing how people voted for specific bills.