This will be the first post out of a 5 part Fun With Data series on congressional data. All of the data comes from the Brooking’s institute (pulled from wiki for this) and the GDP data comes from this excel spreadsheet.

As the elections are coming up, the major focus is on the presidential race. It becomes easy to forget about the congressional races, particularly with such a media crazy election. In my Fun with Congressional Data series (which I will release each Thursday until they are all posted at 3 P.M. Central) I’m going to take a look at:

  1. This post: Party Majority after election in the House/Senate since 1931 and a congressional majority’s connection to changes in Real/Nominal GDP.
  2. Occupation status of congress since 1953.
  3. Percentages of Congress and House/Senate of Democrats and Republicans since 1857.
  4. The myth of independent representation and choices in 2016.
  5. Amount of $$ spent on elections by Incumbents vs. Challengers and it’s effect on re-election since 1974.

But let’s start with this post. In my semester training for becoming a Journalist, we learned to put the most important and grabbing information at the front of the article, so for this post I’m starting with the some of the more interesting info-graphics.

Let’s look at the connection between the majority party and Real GDP, which is adjusted for inflation, below because this was of great interest to me. It should be noted that the % change in real GDP is computed as a difference between the starting GDP of each year and the ending GDP of each year so although the midterm elections are in November, voters are still able to see the writing on the wall in terms of economic shifts.


The data I looked at only had real GDP calculated since 1930, so I looked at the election year GDP and what party won a congressional majority in comparison. There’s a lot of blue dots here! Democrats have had a majority in congress 31 times since 1930 compared to 12 times for republicans, with more Republican majorities occurring more recently.

It doesn’t seem that voters are too concerned with economic performance when voting for a new congress. Major reductions in Real GDP % don’t usually cause voters to change the party majority in congress, but there are a few cases of this. The first case was in the 1932 elections when unemployment rose to 25% during the Great Depression switching power from the Republicans to the Democrats. Although there was less economic constriction the year after the Republicans took a majority, the real GDP % change decreased by over 5% from 1931-1932. The proportion of Democrats changed from 49.71% (a small Republican majority) to 70.05%! This constitutes the largest change in party proportions in congress since 1930.

The second case of voters changing congress over economic performance was in 1946 which was a year after the end of World War 2. In 1944, the economy grew by 8% and in 1945 the economy constricted by 1%. But in 1946, the economy constricted by 11.6%, which is the second largest constriction of the U.S. economy since 1930. Voters decreased the percentage of Democrats from 56.5% to 43.87%, possibly due to this constriction. The final case switched from Democrats to Republicans in 1952 after GDP growth dropped from 8.7% in 1950 to 4.1% in 1952, but this change only amounted to a 53.1% Democrat majority to a 48.77% Democrat minority.

Aside from these 3 cases, you might notice that many times when there was a large adjustment in GDP % change, the majority party stayed in power. Out of the ten election years that oversaw a constriction in the economy, only two saw a switch in the congressional majority. So it doesn’t appear that voters are making sweeping changes due to economic shifts (at least due to real GDP). Now let’s take a look at the nominal GDP  % change (in current dollars) to see if this trend was still prevalent, which doesn’t adjust for inflation.



For nominal GDP, we see the same trends, except the case in 1952 now represents a much smaller decrease in the annual U.S. growth from the Democratic congress in 1950 to the Republican one in 1952. In this case, there were only 8 years (including non election ones) where the nominal GDP was negative. Only three of these fell in between party shifts of elections. Anyways, I thought this was a good starting point for the “Fun with Congressional Data” series leading up to the election. Voters don’t seem to vote based on the economy and are instead driven more by social issues and war.

Next Thursday I’ll take a look at some of the occupations of congress over the years to see if some of the recent mess is due to a certain occupation being more or less represented as a proportion of congress.

If you enjoyed this post, take a look at some of my other Adventures in Statistics.

-Andrew G. Chapple

*I considered the party of each individual at the time they were elected. This avoids the issue of people that change parties midway through their term.


2 thoughts on “Fun With Congressional Data: A look through time at the Congressional Majority Party and it’s connection to GDP

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