Republican Bias of the Senate

In posts from recent weeks, I wrote about how the Senate underrepresents citizens from populous states and minorities.  However, the Senate has also consistently underrepresented Democratic voters for the past 30 years.  Over the past three decades, the Senate has favored the Republican Party.  Since 1980, there have been 17 sessions of Congress.  Democrats have held the majority in the Senate 9 out of 17 sessions, or 52.9% of the time.  However, the population represented by Democratic Senators has been greater than the population represented by the Republicans 15 out of 17 sessions, or 88.2% of the time.  Democrats have been underrepresented in the Senate by between 5 – 18.5% every year since 1980.  If the Senate were apportioned based on population, Democrats would have held the majority in many more sessions of Congress, which has a multitude of policy implications in areas including environmental regulation, health care, and assistance for the poor.  Below are several figures that depict this state of affairs.

The above figure shows the percentage of the Senate that is controlled by each party.  The dashed lines show the percentage of the population that each party represents.  For instance, each Senator from California represents approximately 18.5 million people, while each Senator from Wyoming represents 270,000 people.  The figure shows that the Republican Party is consistently overrepresented in the Senate, while the Democratic Party is underrepresented.
This figure shows the Senators that each state has elected since 1980.  Blue areas represent Democrats and Independents, and red areas represent Republicans.  The data for this plot came from this website.

The above figure shows the percentage increase or decrease in representation relative to population that each party receives because each state gets an equal number of Senators.  These lines were created by subtracting the dashed lines from the solid lines in the first figure.  In 1994, there were an unusually high number of Democratic Senators in populous states.

This figure shows the total misrepresentation in the Senate, which is the sum of the differences in population and senate representation for both major parties.  For example, in 2002, the Democrats only held the Senate Majority with one Senator, giving them a 1% advantage in the Senate.  However, Democratic Senators represented 15.8% more of the population than Republican Senators, which means that in 2002, the Senate misrepresented the population by -14.8%.

The last two figures show the advantage in seats and in population that each party had in the Senate for each session since 1980.  Although the Senate majority has been held in almost equal amounts of time by both parties in the past 30 years, the population voting for Democratic Senators has outnumbered the population which voted for Republican Senators in all but two sessions of Congress.

The figures presented in this post show yet another glaring flaw in the Senate, and consequently, in our entire political system.  The Senate is forming a barrier to social progress by underrepresenting voters in our most populous states, which are often the most diverse, cosmopolitan, technically advanced and socially sophisticated in the country.  California has a population of more than 37 million people, which is greater than the population of the 21 least populous states of 35 million.  The top five most populous states are California, Texas, New York, Florida, and Illinois, which collectively have a population that is larger than the 36 least populous states, 113 million vs. 111 million, respectively.  Over the past 30 years, California has voted for Democratic Senators 80% of the time, and the top 5 most populous states have voted for Democratic Senators 63% of the time.  This Senate is clearly not representing the population well and should be reworked.

16 thoughts on “Republican Bias of the Senate

  1. 、それは休憩を取る瞬間です。私はこの記事を学ぶ持っていると私はちょうど私があなたにいくつかの興味深い問題やアドバイスをお勧めしたい場合があります。たぶん、あなたはこのblogpostを参照し、その後の記事を投稿することができます。私はそれをより多くの問題を研究するために願っています!

  2. Just happened onto this article. Because a filibuster (still applicable to all legislation and supreme court appointments) can be accomplished with just 40 Republican votes, that further skews the Republican “overrepresentation.” You indirectly alluded to this in your response to Constance on Nov 5, 2012. Of course, the makeup of the Senate will change from time to time, but as previously noted, two senators per state, regardless of population, is ensconced in the Constitution and is not going to change in the foreseeable future.

  3. the current setup is to prevent things like gay marriage, universal healthcare, and other progressive things from happening. luckyly ted kennedy could not vote on universal healthcare otherwise we r in big trouble. scott brown for the win 2010. boo yah

  4. Hi,
    Thank you for posting this information and I especially appreciated your response to Chuck Daniels’ comment. I am writing a brief report about the senate and if it is truly a democratic institution and this information has really helped me! Also, I do agree with your arguments, reforms could definitely be made, but since it is such a fundamental part of the constitution, I doubt anything will happen anytime soon.

    • Constance, sorry to take so long to respond. I didn’t see your comment in the WP dashboard. I’m glad you enjoyed reading the article. I agree that the Senate will be with us for a long time, barring a revolution. Reform of the Senate rules to stop a filibuster with a simple majority could be accomplished, and I support this reform.


  5. In 1910 rural areas had 72% of the population of America. By 1950 it was still over half. And what is it today? 16%. Usually people who are more forward looking are inclined to move. This means that rural areas not only lose population. They become more conservative. The idea that rural areas are “America’s heartland”, is nonsense. And the idea that the media should get all wrapped up in covering primary races in these areas, is even more nonsensical!

  6. It is your argument, not the Senate which needs to be reworked. The Senate is not supposed to be based on population and is intended to provide equal representation to all states, hence the number of Senators (2) for each state regardless of the amount of constituents. Rural areas being overrepresented and urban states being underrepresented is not a “glaring flaw in the Senate” as you claim; it is a mechanism to prevent densely populated states (read: wealthy) from monopolizing the legislative process. Otherwise the needs and opinions of people living in rural (read: poorer) states would be drowned out by the “diverse, cosmopolitan, technically advanced and socially sophisticated” voices of the most populous states.

    • Dear Chuck,

      Thanks for comment. I appreciate your input. I understand that the Senate is not supposed to be based on population. However, the ratio of the population between the most populous and least populous states is far higher today than when the Constitution was written. For instance, the ratio between the largest and smallest states in 1790 was 11:1, Virginia to Delaware. Now, that ratio is 66:1, California to Wyoming. In the original thirteen states, this was somewhat unreasonable, but still palatable. Today, individuals in large states are far underrepresented compared to their counterparts in smaller states.

      I looked into your claim about people in larger states being wealthier than those in smaller states and found that it is not true. Larger states do have a higher state GDP than smaller states, but do not have a higher state GDP per capita. I ran a quick correlation on state population and per capita GDP based on data from Wikipedia ( and found that there is a correlation of -0.08 between the two data sets. There is no link between state population and per capita GDP. The people in large states are just as wealthy as people in small states. If we got rid of equal representation for states, there is no evidence that rich people would take advantage of poor people any more than they are doing now.

      Equal state representation only serves to create irregularities such as extremely powerful Senators from states like Alaska and Hawaii or massive ethanol subsidies to the Upper Midwest states. The removal of equal state representation would definitely decrease the power of people living in smaller states, but this decrease would be to an appropriate level. People living in North Dakota or Alaska do not deserve 30x the voting power of people living in Florida or New York. Making this change would make the US more democratic, and give each person an equal representation.


      • Eric,

        You seem like a crybaby who still thinks Bush stole the election.
        How about having the dems change their policies

        • I never made the claim that Bush stole the election. Perhaps you should focus on my arguments rather creating them. Furthermore, your suggestion is so broad as to be meaningless.

          • why dont the dems just move to states like wyoming and take over? most of them are on food stanps so finding a job will not be an issue

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