By: Tyler Curry

On the first Tuesday, after the first Monday, of every even year, Republicans and Democrats vie for a seat on the United States Congress. Popular discussion suggests that voters are amid what could be a threshold of Republican majority.

We compared historical data revealing the Democratic and Republican majority states elected, dating back to every even year since 1994, in order to gain a more contextual understanding of house and senate majorities.

An article in The New Republic cited a political trend – congress has typically been in opposition with the winning presidential party – particularly within the House of Representatives. As noted by Political Scientist, James E. Campbell, “… midterm elections reduce the number of seats held by the President’s party.”

According to Campbell’s Referendum Theory of midterm elections, voters swing their congressional votes based on their approval of Presidential parties. Each midterm outcome is supposed to say something meaningful about the popular views of the country.

We compared historical data to look further into this theory.


Since 1994, Republicans have typically represented the House majority while Democrats withheld Senate majority.

Data breaks down 1
House of Representative seats lean in favor of the Republican Party, with the exceptions of the 2006 and 2008 elections.

Data breaks down 2

Democrats had a small margin in terms of congressional majority, back in 2006. But that trend continued through 2008 with nearly 10 more blue states than in the 2006 election.Data breaks down 3

Data breaks down 4

States such as Missouri, Ohio, Virginia and several coastal states which could have gone either way, swinging between a 40% – 60% voting average per party in 2006. And again in 2008, the map shows Democrats at an increased marginal percentage – making all the difference in the House of Representatives.

Similar patterns can be found in the Senate election outcomes during years 1994, 2002 and 2010, where the majority was atypically in favor of the Republican Party.

Data breaks down 5

Charted data shows the Democratic Party is a historical majority ruler of the Senate, but powers were usurped by Republicans on three isolated occasions since 1994.

Data breaks down 6

Several swing states across the U.S. tipped red in the 1994 Senate elections. In 2002, the margins were lower but Republican voters had a stronger presence among previously red states between 80% – 100%.

Data breaks down 7

Data breaks down 8

According to data, party votes per year showed a slight margin in 2010, but was returned back to Democrats in 2012.

Wondering what this all means and why it matters? Polls open for the 2014 congressional elections on November 4th. The New Republic’s reference to James Campbell and other theorist who believe the political tendency is that the outcome of congressional majority is to highlight the attitudes of the nation.

As the President’s approval rating continues to decline (according to a recent poll) and apathetic potential voters remain unregistered, a few considerations come to fore about what meaningful inferences can be made based on the 2014 outcome. Will the votes be reflective of a civically active population, evenly disbursed among Democrat and Republican voters?  How might the outcome of the 2014 Congressional elections affect voter attitudes in the 2016 Presidential race?