The ideological middle in Congress is an endangered species. And, contrary to popular belief, it may not be the fault of politicians.
Many have speculated that congressional redistricting, which occurs every 10 years, is a major culprit. As the theory goes, districts are made politically safer for incumbents, which means they cater more to the majority and neglect the minority.
However, Chris Cillizza of the Washington Post says data may not support that theory. He cites the work of a trio of political science professors who wrote a paper titled, "Does Gerrymandering Cause Polarization?" Their answer is "no."