Elections to the U.S. House will be held on November 6, 2018. All 435 seats will be up for election. Special elections were held earlier in 2018 and in 2017 to fill vacancies that occurred in the 115th Congress.

As of October 2018, the Republican Party was in the majority, holding 235 seats to Democrats' 193 seats, with seven seats being vacant. Democrats need to have a net gain of 23 Republican seats to win the House. Click here to see the 2018 battleground House races identified by Ballotpedia.

The Democratic Party is well-positioned to gain seats, according to a 100-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. In the 20 percent of elections where the president lost the most seats—which Ballotpedia defined as wave elections—his party lost at least 48 seats.

Fifty-six U.S. representatives did not seek re-election, either retiring or seeking higher office. Click here to see a full list of departing incumbents.

Thirty-eight seats up in 2018 were won by the presidential candidate of the opposite party in 2016: Hillary Clinton (D) won 25 Republican-held districts and Donald Trump (R) won 13 Democratic-held districts. Read more below.

Ballotpedia covered every state and federal primary in 2018 to highlight the intraparty conflicts that shaped the parties and the general elections. Click here for our coverage of Republican Party primaries in 2018, and here for our coverage of Democratic Party primaries.

Partisan breakdown

Following the 2016 general election, the Democratic Party gained six seats. They picked up seven seats while losing one in Nebraska. The Democratic Party fell short of the 30 seats required to retake the chamber. After flipping a Republican seat in Pennsylvania in a February 2018 special election, the Democratic Party would need to pick up 23 seats in 2018 to win the chamber.^[1]

Battlegrounds

See also: U.S. House battlegrounds, 2018

This is a list of the U.S. House battlegrounds in 2018.

The following map identifies those races that are considered battleground elections. Mouse over a district for more detailed information. You can also zoom in for a closer look.

Criteria

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 be competitive in 2018 than just those that meet 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.

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 supported Hillary Clinton in 2016 is more likely to be vulnerable than a Republican incumbent in a district that backed President Donald 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.

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.

5. Outside race ratings:

Race ratings from other outside sources like the Cook 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.

SEE INTERACTIVE MAP

https://ballotpedia.org/United_States_House_of_Representatives_elections,_2018