Amazing graphic from LPDonovan showing how Polarized the US Senate (and likely the country) has become in just 24 years. In 1989 there was quite a bit of issues that the Senate could agree on indicated by the Purple and the close proximity of the individual Senators. In 2002 (George W Bush as President) again the country was not divided as the image shows both purple in the middle and plenty of overlap.
Fast Forward to 2013 (Barack Obama as President). There is virtually no overlap or purple showing. Most all votes are straight party line votes. The country is a polarized as it has ever been. Interesting: