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Wave elections (1918-2016)/Evaluating 2018
 |
House waves • Senate waves • Gubernatorial waves • State legislative waves |
Competitiveness in State Legislatures |
June 19, 2018
By: Rob Oldham and Jacob Smith
To determine the seat changes necessary for 2018 to qualify as a wave election, we applied our definition to the current partisan breakdown of the seats up for election in 2018.
The chart below shows the partisan breakdown of those seats:
| Pre-November 2018 | ||||||
|---|---|---|---|---|---|---|
| Election year | Election group | Democratic seats | Republican seats | Democratic seat share | Republican seat share | |
| 2016 | U.S. House[1] | 195 | 240 | 44.8% | 55.2% | |
| 2012 | U.S. Senate | 26[2] | 9 | 74.3% | 25.7% | |
| 2014 | Gubernatorial[3] | 9 | 26 | 25.0% | 72.2% | |
| 2016 | State legislative[4] | 3130 | 4178 | 42.8% | 57.2% | |
Based on our analysis of historical elections, we applied the following definitions:
- U.S. House—Democrats gain 48 seats
- U.S. Senate—Democrats gain seven seats
- Gubernatorial races—Democrats gain seven seats
- State legislative races—Democrats gain 494 seats
This chart shows what each election group must look like after the 2018 elections for Ballotpedia to consider it a wave:
| Post-2018 breakdown for a wave | ||||||
|---|---|---|---|---|---|---|
| Election group | Democratic seats | Republican seats | Margin | Democratic seat share | Republican seat share | |
| U.S. House[1] | 243 | 192 | D+51 | 55.9% | 44.1% | |
| U.S. Senate | 33 | 2 | D+31 | 94.3% | 5.7% | |
| Gubernatorial[3] | 16 | 19 | R+3 | 44.4% | 52.8% | |
| State legislative[4] | 3624 | 3684 | R+60 | 49.6% | 50.4% | |
It will not take wave elections for the Democrats to take back the House or the Senate. However, Democrats will need waves and then even further gains to take control of a majority of the country's governorships and state legislative seats.
| What Democrats need in 2018 | ||
|---|---|---|
| Election group | Seats needed for chamber/majority control | Seats needed for a wave election |
| U.S. House | D+23[1] | D+48 |
| U.S. Senate | D+2 | D+7 |
| Gubernatorial | D+10 | D+7 |
| State legislative | D+525[4] | D+494 |
Click here to read the report as one page.
Click here to read or download the report as a PDF.
Footnotes
- ↑ 1.0 1.1 1.2 This number was calculated in April 2018 and assumed that Republicans would have a 240-195 majority at the time of the 2018 elections.
- ↑ Independents Bernie Sanders (Vermont) and Angus King (Maine) are counted as Democrats.
- ↑ 3.0 3.1 Gov. Bill Walker (I-Alaska) is not included.
- ↑ 4.0 4.1 4.2 Totals were calculated following the 2016 elections and do not account for elections in 2017 or early 2018.
