U.S. House battlegrounds, 2018
TheDemocratic Party won control of theU.S. House from theRepublican Party onNovember 6, 2018. Democrats gained a net total of 40 seats, 17 more than the 23 seats they needed to win control of the House.
Heading into the elections, Republicans had a 235-193 majority with seven vacancies. Ballotpedia identified 82U.S. Housebattleground races: 73Republican seats and nineDemocratic seats. At least 43 of the Republican-held battleground seats were won by Democrats and three of the Democratic-held battleground seats were won by Republicans.
We determined battleground seats using, among other factors, past election results, presidential election results, retirement data, and outside race ratings.Click here to learn more about our methodology.
2018 election analysis and context
All 435 seats—including seven vacancies—were up for election, with Democrats needing to add 23 seats to win majority control of the chamber.
The Democratic Party was well-positioned to gain seats, according to a100-year historical analysis of House elections conducted by Ballotpedia and political scientist Jacob Smith.From 1918 to 2016, the president’s party lost an average of 29 seats in midterm elections. The Democrats matched this pattern in the 2018 midterms, gaining 40 seats for a total of 235 seats—17 more than was needed for a majority.
One undecided 2018 race was decided in September 2019 whenDan Bishop (R) won thespecial election. The state board of elections called a new election following allegations of absentee ballot fraud in the2018 race.Click here for more information on the aftermath of the 2018 election.
In 372 of the 435 seats, an incumbent was seeking re-election on November 6. There were52 seats where the incumbent was either retiring or otherwise not seeking re-election—18 Democrats and 34 Republicans, including House SpeakerPaul Ryan (R-Wisconsin)—and seven vacant seats. In four other seats, the incumbent—two from each party—was defeated in a primary before election day.
There were 46 seats that changed party hands, both open seats and those occupied by an incumbent, and 30 of the 372 incumbent U.S. representatives (8.1 percent) lost their seats in the general election—allRepublicans.
Thirty-eight seats up in 2018 were won by the presidential candidate of the opposite party in2016:Hillary Clinton (D) won 25 Republican-held districts, andDonald Trump (R) won 13 Democratic-held districts. On November 6, 2018, Democrats won 22 of the25 Clinton-leaning seats held by Republicans after 2016, while Republicans won two of the13 Trump-leaning seats held by Democrats.
Partisan breakdown
The table below shows the partisan breakdown of the U.S. House of Representatives before and after the 2018 mid-term elections.
| U.S. House Partisan Breakdown | |||
|---|---|---|---|
| Party | As of November 5, 2018 | After the 2018 Election | |
| Democratic Party | 193 | 235 | |
| Republican Party | 235 | 200[1] | |
| Vacancies | 7 | 0 | |
| Total | 435 | 435 | |
After flipping a Republican seat in Pennsylvania in aFebruary 2018 special election, the Democratic Party needed to pick up 23 seats in 2018 to win the chamber.[2]
Battlegrounds
This is a list of the U.S. House battlegrounds in 2018.
The following map identifies those races that were considered battleground elections. Mouse over a district for more detailed information. You can also zoom in for a closer look.
Criteria
- See also:Battlegrounds
The following criteria were the primary means for determining if a race was expected to be competitive in 2018. No specific number of criteria has to be met to label a district competitive, but all were considered in each race. More races could have been competitive in 2018 than just those that met our criteria.
1. Margin of victory (MOV) in the past House elections:
- The MOV of the district in previous elections is one of the primary methods for estimating the potential competitiveness of a district in the future. Ballotpedia considers competitive races to be those with a MoV of less than 10 percent.
- The MOV of the district in previous elections is one of the primary methods for estimating the potential competitiveness of a district in the future. Ballotpedia considers competitive races to be those with a MoV of less than 10 percent.
2. Margin of victory in the past presidential elections:
- Like the MOV in past congressional elections, how a president fared in each congressional district is a big indicator of the political climate in a district. For instance, a Republican incumbent in a district that supportedHillary Clinton in 2016 is more likely to be vulnerable than a Republican incumbent in a district that backed PresidentDonald Trump.
- Like the MOV in past congressional elections, how a president fared in each congressional district is a big indicator of the political climate in a district. For instance, a Republican incumbent in a district that supportedHillary Clinton in 2016 is more likely to be vulnerable than a Republican incumbent in a district that backed PresidentDonald Trump.
3. Open seats:
- Incumbents have extremely high re-election rates. In 2016, 96.7 percent of congressional incumbents who sought re-election won. An open seat is traditionally far more vulnerable than one in which the incumbent is seeking re-election, even if the incumbent is unpopular.
- Incumbents have extremely high re-election rates. In 2016, 96.7 percent of congressional incumbents who sought re-election won. An open seat is traditionally far more vulnerable than one in which the incumbent is seeking re-election, even if the incumbent is unpopular.
4. Time spent in office:
- The number of terms an incumbent has spent in office has an impact on how vulnerable they may be. Freshmen incumbents tend to be more vulnerable than those who have served multiple terms in office.
- The number of terms an incumbent has spent in office has an impact on how vulnerable they may be. Freshmen incumbents tend to be more vulnerable than those who have served multiple terms in office.
5. Outside race ratings:
- Race ratings from other outside sources like theCook Political Report were considered when making our initial list of battlegrounds.
- Race ratings from other outside sources like theCook Political Report were considered when making our initial list of battlegrounds.
6. Special highlights:
- Special highlights could include anything from a rematch of the 2016 House race, to an incumbent made vulnerable due to a scandal. Any special circumstances will be taken into account here.
Wave election analysis
- See also:Wave elections (1918-2016)
The termwave election is frequently used to describe an election cycle in which one party makessignificant electoral gains. How many seats would Republicans have had to lose for the 2018 midterm election to be considered a wave election?
Ballotpedia examined the results of the 50 election cycles that occurred between 1918 and 2016—spanning from PresidentWoodrow Wilson's (D) second midterm in 1918 toDonald Trump's (R) 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.
Applying this definition toU.S. House elections, we found that Republicans needed to lose48 seats for 2018 to qualify as awave election.
The chart below shows the number of seats the president's party lost in the 11 U.S. House waves from 1918 to 2016.Click here to read the full report.
| U.S. House wave elections | ||||||
|---|---|---|---|---|---|---|
| Year | President | Party | Election type | House seats change | House majority[3] | |
| 1932 | Hoover | R | Presidential | -97 | D | |
| 1922 | Harding | R | First midterm | -76 | R | |
| 1938 | Roosevelt | D | Second midterm | -70 | D | |
| 2010 | Obama | D | First midterm | -63 | R (flipped) | |
| 1920 | Wilson | D | Presidential | -59 | R | |
| 1946 | Truman | D | First midterm | -54 | R (flipped) | |
| 1994 | Clinton | D | First midterm | -54 | R (flipped) | |
| 1930 | Hoover | R | First midterm | -53 | D (flipped) | |
| 1942 | Roosevelt | D | Third midterm | -50 | D | |
| 1966 | Johnson | D | First midterm[4] | -48 | D | |
| 1974 | Ford | R | Second midterm[5] | -48 | D | |
Competitiveness
Ballotpedia's Annual Congressional Competitiveness Report found the following:
- There were 55 open seats in 2018.
- There were 42 House seats where only one major party ran a candidate.
- Nine House incumbents from districts won by the opposite party's presidential candidate in 2016 did not seek re-election.
Presidential data
- See also:Presidential election, 2016
According toDaily Kos' 2016 presidential results by congressional district data,Hillary Clinton (D) won 207 of the congressional districts up in 2018, whileDonald Trump (R) won 228 districts. There were 25 Republican-held districts Clinton won and 13 Democratic-held districts Trump won.[6]
Republican/Clinton districts
The 25 Republican-held districts voted for Clinton by as many as 28.2 percentage points and as few as 1.1 percentage points. In 2012, 13 voted forMitt Romney (R) and 12 voted forBarack Obama (D). Although they were scattered across the country, 11 of the districts were located inCalifornia orPennsylvania.
Four districts did not exist during the 2016 election and were created after thePennsylvania Supreme Court ruled that the state's previous congressional map was unconstitutionally gerrymandered to favor Republicans. The redrawing increased the number of Clinton/Republican districts in Pennsylvania from two to four.
There were eight House seats that supported the Republican nominee in 2008 and 2012 (McCain andRomney) that were won byHillary Clinton in 2016:AZ-02,CA-39,CA-45,CA-48,KS-03,NJ-07,TX-07, andTX-32
Democratic/Trump districts
The 13 Democratic districts voted for Trump by as many as 30.8 percentage points and as few as 0.7 percentage points. In 2012, four voted forMitt Romney (R) and nine voted forBarack Obama (D). Although they were scattered across the country, nine of the 11 districts were located in the midwest or the northeast, with five being inMinnesota orPennsylvania.
Conor Lamb (D) won a 2018special election in Pennsylvania to replace U.S. Rep.Tim Murphy (R). This increased the number of Trump/Democratic districts in Pennsylvania from one to two. Both districts were redrawn after thePennsylvania Supreme Court ruled that the state's previous congressional map was unconstitutionally gerrymandered to favor Republicans.
There were 20 House seats thatBarack Obama won in 2008 and 2012 that were won byDonald Trump in 2016:IA-01,IA-02,IA-03,IL-12,IL-17,ME-02,MN-01,MN-02,MN-08,NH-01,NJ-02,NJ-03,NV-03,NY-01,NY-02,NY-18,NY-19,NY-21,PA-17, andWI-03.
Comparison of retirements
The following table includes figures on Democratic and Republican members of Congress who either left office during their term or announced that they would not seek re-election for each election year since 2012.
| Outgoing members of Congress, 2012-2018 | |||||||
|---|---|---|---|---|---|---|---|
| Year | Chamber | Democrats not seeking re-election | Republicans not seeking re-election | Total not seeking re-election | Democrats leaving office early | Republicans leaving office early | Total leaving office early |
| 2018 | |||||||
| U.S. Senate | 0 | 3 | 3 | 1 | 2 | 3 | |
| U.S. House | 18 | 34 | 52 | 3 | 14 | 17 | |
| Total | 18 | 37 | 55 | 4 | 16 | 20 | |
| 2016 | |||||||
| U.S. Senate | 3 | 2 | 5 | 0 | 0 | 0 | |
| U.S. House | 16 | 24 | 40 | 2 | 5 | 7 | |
| Total | 19 | 26 | 45 | 2 | 5 | 7 | |
| 2014 | |||||||
| U.S. Senate | 5 | 2 | 7 | 3 | 2 | 5 | |
| U.S. House | 16 | 25 | 41 | 3 | 6 | 9 | |
| Total | 21 | 27 | 48 | 6 | 8 | 14 | |
| 2012 | |||||||
| U.S. Senate | 6 | 3 | 10[13] | 0 | 0 | 0 | |
| U.S. House | 23 | 20 | 43 | 4 | 1 | 5 | |
| Total | 29 | 23 | 53 | 4 | 1 | 5 | |
Cook Partisan Voter Index
The chart above details the 2017 Cook Partisan Voter Index for each U.S. House district. The index, developed by Charles Cook of theThe Cook Political Report, compares each congressional district's score to that of the nation as a whole. According toPolitico, the PVI is designed to "provide a quick overall assessment of generic partisan strength in a congressional district."[14][15][16]
Outside race ratings
The following table compares the most recent race ratings fromThe Cook Political Report,Sabato's Crystal Ball, andInside Elections.
See also
- United States Congress elections, 2018
- United States House of Representatives elections, 2018
- United States House of Representatives
Footnotes
- ↑One undecided 2018 race was decided in September 2019 whenDan Bishop (R) won thespecial election. The state board of elections called a new election following allegations of absentee ballot fraud in the2018 race. Unofficial returns from the 2018 election showedMark Harris (R) leading McCready, who was also the Democratic candidate in 2018, by 905 votes. Harris said he did not run again in 2019 due to health issues.Click here for more information on the aftermath of the 2018 election.
- ↑The New York Times, "House Election Results: G.O.P. Keeps Control," accessed November 15, 2016
- ↑Denotes the party that had more seats in the U.S. House following the election.
- ↑Lyndon Johnson's (D) first term began in November 1963 after the death of President John F. Kennedy (D), who was first elected in 1960. Before Johnson had his first midterm in 1966, he was re-elected president in 1964.
- ↑Gerald Ford's (R) first term began in August 1974 following the resignation of President Richard Nixon (R), who was first elected in 1968 and was re-elected in 1972. Because Ford only served for two full months before facing the electorate, this election is classified as Nixon's second midterm.
- ↑Daily Kos, "Daily Kos Elections' presidential results by congressional district for the 2016 and 2012 elections," accessed February 8, 2017
- ↑The new 1st district was created in early 2018 due to court-ordered redistricting and most closely resembles the old 8th District held by Fitzpatrick.Click here to read more.
- ↑The new 5th district was created in early 2018 due to court-ordered redistricting and most closely resembles the old 7th District held by Meehan.Click here to read more.
- ↑The new 6th district was created in early 2018 due to court-ordered redistricting and most closely resembles the old 6th District held by Costello.Click here to read more.
- ↑The new 7th district was created in early 2018 due to court-ordered redistricting and most closely resembles the old 15th District held by Dent.Click here to read more.
- ↑The new 8th district was created in early 2018 due to court-ordered redistricting and most closely resembles the old 17th District held by Cartwright.Click here to read more.
- ↑The new 14th district was created in early 2018 due to court-ordered redistricting and most closely resembles the old 18th District Lamb won in aMarch 2018 special election.Tim Murphy (R) won the old 18th District in the 2016 election.Click here to read more.
- ↑Figure includes Sen.Joe Lieberman (I-Conn.).
- ↑Politico, "Charlie Cook's PVI," April 10, 2009
- ↑RedState, "New Cook PVIs Show Big Opportunities for Conservatives in the House," October 11, 2012
- ↑Swing State Project, "Just what is the Partisan Voter Index (PVI)?" November 16, 2008
