Wave elections (1918-2016)
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House waves • Senate waves • Gubernatorial waves • State legislative waves |
Competitiveness in State Legislatures |
June 19, 2018
By: Rob Oldham and Jacob Smith
The term wave election is frequently used to describe an election cycle in which one party makes significant electoral gains. With the 2018 midterms approaching, pundits have written about the possibility of a wave election against Donald Trump's (R) presidency and the Republican Party.
How many seats would Republicans have to lose for the 2018 midterm election to be considered a wave election? That's a hard question to answer because there is no official or consensus definition of the term wave election.
In this paper, we examine the results of the 50 election cycles that occurred between 1918 and 2016—spanning from President Woodrow Wilson's (D) second midterm in 1918 to Trump's first presidential election in 2016. We define wave elections as the 20 percent of elections in that period resulting in the greatest seat swings against the president's party.[1]
We apply this definition to four different election groups: U.S. Senate, U.S. House, governorships, and state legislatures.
Applying this definition to the 2018 midterms yields specific numbers of seats that Republicans would need to lose in each group of elections for the term wave election to apply. Republicans would need to lose 48 U.S. House seats, seven U.S. Senate seats, seven gubernatorial seats, and 494 state legislative seats for each group of elections to qualify historically as a wave against the president's party in November 2018. Read more about the 2018 elections below.
Our objective in this paper is threefold:
- Contribute to a conversation among political scientists and pundits about whether it is possible or desirable to provide an objective definition of the term wave election
- Put forward our own specific methodological proposal for how to define a wave election
- Apply our methodology to historical elections to derive and propose specific numbers of lost seats that should set the benchmark for what is considered a wave election in 2018
How to read this report
First, we review our methodology.
We then introduce a discussion of the term wave election and use our definition to evaluate the 2018 elections.
After that, we present our analyses of each election group:
Next, we present our analyses of:
- Years where multiple waves occurred
- Years where waves go toward the president's party
- How the type of election—first midterm, second midterm, or presidential—affects the prospects of a wave occurring
- A comparison of waves from 1918-2016 and waves from 1946-2016
- The effectiveness of the out of power party in gaining seats
- How waves have impacted control of the U.S. House since 1918
Finally, we present limitations of our study, the data we used, and opportunities for further analysis.
Click here to read the report as one page.
Click here to read or download the report as a PDF.
Methodology
The methodology we propose has three guideposts:
- The term wave election is a relative term used to compare outcomes in one year to elections in another year. To define the term, then, requires looking at a considerable wealth of historical and contextual detail.
- The term wave election as it is used implies significant change. It should be a clearly large effect.
- The term wave election should be separately applied to groups of elections; we want to be able to say of a given election year that whereas there was a wave election in the U.S. House, this did not happen at the level of state governorships. Or, conversely, we would like to be able to say, "In this election year, there was a wave election in the U.S. House that also extended to state governorships and state legislatures."
We ranked partisan changes in 50 elections and placed them in five quintiles according to the net seat change by the president's party. We define a wave for each election group — U.S. House, U.S. Senate, governors, and state legislative elections—as one in which the net seat change by the president's party falls into the top quintile of historical changes.
Our data consists of the gains or losses for the president's party in U.S. House, U.S. Senate, gubernatorial, and state legislative elections. For more, see this section.
For additional context, we divided the elections into three types: a president's first midterm, his second midterm, or a presidential election year.[2]
To learn more about our methodology, including why we used a quintile analysis, visit this section.
About the authors
Rob Oldham is a staff writer on Ballotpedia's Marquee Team
Jacob Smith will be a Lecturing Fellow in the Thompson Writing Program at Duke University
Ballotpedia staff writers Emily Aubert, Paul Rader, and Sara Reynolds assisted with data collection and research. Heidi Jung developed the graphics.
Ballotpedia CEO Leslie Graves, Editor-in-Chief Geoff Pallay, and Editor-at-Large Scott Rasmussen reviewed the report and provided feedback as did editors Cory Eucalitto, Christopher Nelson, Sarah Rosier, and Kristen Smith. Outside reviewers included Norm Leahy and Steve "Nemo" Nemerovski.
Footnotes
- ↑ Although they are not the focus of this report, we also discuss wave elections that swing toward the president's party, which we call presidential wave elections. Click here for more.
- ↑ Franklin Roosevelt (D) had a third midterm election in 1942. He is the only president to have more than two midterms.