What's clear from the chart is that while Senate Democrats are more closely aligned than Republicans in their voting patterns so far in 2013 -- Wilson notes that 22 Democrats have voted exactly the same on every vote this year -- there are very few ties between the two parties. The two members sitting in the middle are Republicans Sens. Lisa Murkowski (Alaska) and Susan Collins (Me.), two of the noted moderates in the chamber.
Then there is the strange case of Louisiana Sen. David Vitter (R) and New Jersey Sen. Frank Lautenberg (D). Neither man has voted with any other senator more than 75 percent of the time during 2013. (Lautenberg, who is retiring in 2014, hasn't even voted with any other Senator 65 percent of the time.)
The most obvious storyline from the amazing tool Wilson has built is that the two parties in the Senate have, at least by their voting records in 2013, almost nothing in common. That affirms the widening partisan divide that we've observed in the Senate and in politics more broadly over the past few years.
Fiddle around with Wilson's infographic. It's a great tool that can spawn a thousand insights into how the Senate works (and doesn't). What's yours?