If you're looking for a quick fact to explain congressional gridlock, it's this: In the 113th Congress, only 59 members have voted with the majority of their party less than 90 percent of the time (20 Republicans and 39 Democrats).
The trend over the last 30 years is that Congress has become increasingly sorted into political blocs that vote only with each other. According to National Journal's vote ratings, 30 years ago most lawmakers had records that put them somewhere in between the most liberal Republican and the most conservative Democrat. Now there are just a relative handful.
As you can clearly see in this chart of the 113th Congress House votes, most representatives vote with the majority of their party (data via OpenCongress). That lonely blue dot at the bottom is Jim Matheson of Utah, a Democrat, who represents a conservative district.
House Members by Percentage of Votes With Respective Party Majority
Roll over a circle for more information or click and drag on the chart to zoom into a specific area.
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