Become part of the movement for unbiased, accessible election information. Donate today.
Wave elections (1918-2016)/Multiple waves
 |
House waves • Senate waves • Gubernatorial waves • State legislative waves |
Competitiveness in State Legislatures |
June 19, 2018
By: Rob Oldham and Jacob Smith
The sections below show election years as whole rather than individual election groups like the U.S. House or state legislative seats.
We provide our definition of a tsunami election year and a composite analysis that combines our measures of wave elections into a single figure.
Tsunami election years
A tsunami election year occurs when waves appear in at least three election groups. Specifically, tsunamis occur when waves appear in both U.S. House and state legislative elections and at least one wave appears in either U.S. Senate or gubernatorial elections.
Based on this definition, tsunami elections occurred in 1920, 1922, 1930, 1932, 1938, 1966, and 2010.
| Tsunami election years (1922-2016) | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Year | President | Party | Election type | U.S. House wave | U.S. Senate wave | Gubernatorial wave | State legislative wave | ||
| 1920 | Wilson | D | Presidential | ✔ | ✔ | ✔ | |||
| 1922 | Harding | R | First midterm | ✔ | ✔ | ✔ | |||
| 1930 | Hoover | R | First midterm | ✔ | ✔ | ✔ | ✔ | ||
| 1932 | Hoover | R | Presidential | ✔ | ✔ | ✔ | ✔ | ||
| 1938 | Roosevelt | D | Second midterm | ✔ | ✔ | ✔ | |||
| 1966 | Johnson | D | First midterm[1] | ✔ | ✔ | ✔ | |||
| 2010 | Obama | D | First midterm | ✔ | ✔ | ✔ | |||
Composite analysis
The composite analysis aggregates an overall score for U.S. House, U.S. Senate, gubernatorial, and state legislative races in a given year.
The composite score is an average of the seat share changes for U.S. House, U.S. Senate, gubernatorial, and state legislative races. It is an overall measure of how the presidential party performed in a given year.
To be considered a composite wave election, Ballotpedia determined the presidential party's seat share must decline by an average of more than 14.7 percent across the four election groups. The 10 election years where this occurred are wave election years. Like previous analyses, they are in the top quintile of the 50 election cycles since 1918.
Four of the 10 composite wave elections happened in a president's first midterm election.
The median composite score is -3.8 percent. The average composite score is -5.2 percent.
The chart below shows the 10 composite wave elections. To see the full set of elections from 1918 to 2016, click here.
| Composite wave elections (1918-2016) | ||||||||
|---|---|---|---|---|---|---|---|---|
| Year | President | Party | Election type | Overall score | U.S. House | U.S. Senate | Governor | State legislatures |
| 1932 | Hoover | R | Presidential | -26.3% | -22.3% | -40.6% | -28.6% | -13.9% |
| 1922 | Harding | R | First midterm | -20.7% | -17.5% | -18.8% | -33.3% | -13.1% |
| 1958 | Eisenhower | R | Second midterm | -18.8% | -10.8% | -37.5% | -17.6% | -9.2% |
| 1980 | Carter | D | Presidential | -18.8% | -7.6% | -33.3% | -30.8% | -3.4% |
| 1938 | Roosevelt | D | Second midterm | -18.2% | -16.1% | -18.8% | -27.3% | -10.7% |
| 1930 | Hoover | R | First midterm | -17.5% | -12.2% | -21.9% | -27.3% | -8.7% |
| 1920 | Wilson | D | Presidential | -17.0% | -13.6% | — | -27.8% | -9.6% |
| 1994 | Clinton | D | First midterm | -15.5% | -12.4% | -15.2% | -27.8% | -6.6% |
| 1966 | Johnson | D | First midterm[1] | -15.4% | -11.0% | -14.7% | -25.7% | -10.3% |
| 1942 | Roosevelt | D | Third midterm | -14.8% | -11.5% | -29.0% | -12.1% | -6.7% |
The graphs below show how each election type compares with the U.S. House elections when measured by the percentage change in seats of the president's party.
Click here to read the report as one page.
Click here to read or download the report as a PDF.
Footnotes
