Light red cells indicate elections where the party’s representation in Congress is significantly less than its share of the popular vote.
Bright green cells indicate elections where the loser of the popular vote ends up winning control of Congress.
Senate elections are grouped into 3x blocks, since the entire senate goes up for election over a 6-year election cycle.
Some interesting observations from the above time period:
- In the 40 years from 1968 – 2010, there have only been two instances where the loser of the popular vote won control of congress
- In the 10 years since 2010, it has become the norm for the loser of the popular vote to have control of congress. Including both senate election cycles since 2010
- In every instance where the loser of the popular vote wins control of Congress, the Republicans have been the beneficiaries
- From 1968 – 1990, Republicans were the biggest losers of the electoral system. Almost universally, their representation in Congress was significantly less than their popular vote
- Since 2010, Democrats have become the biggest losers of the electoral system. Their representation in Congress is usually less than their popular vote
- Historically, the House has been far more unfair than the Senate. The Senate has gone through alternating cycles of favoring either party. Whereas the House has been universally unfair to Republicans for a 26 year stretch from 1968 – 1994. And has recently swung the other way. This unfairness in the House is potentially a result of gerrymandered congressional districts
- The Democrats had a multi-decade winning streak from 1968 – 1990, where they won every single popular vote in both the House and the Senate. Including the years when Regan was president. Alternating majorities in Congress have been a recent development
Source – House election results
Source – Senate election results