I have been wondering about state legislative special elections. They are more numerous than House elections, and therefore are likely a better predictor of results.

Relative to the district's performance in 2020 or 2018 in that same race, excluding races where someone died and a widow(er) is running to replace the deceased member, as well as uncontested races in either November 2020 and the special, which party is leading special elections at the state legislative level? Note I am also excluding states where the normal legislative elections aren't held in presidential years. I am also making it so races with runoffs have only the first round counted and not the runoff election.

(For example, New Mexico's 1st and Louisiana's 2nd are the only two federal/House examples. The Democrats overperformed in both races, by 8 and 13 points respectively.)

  • The reason I want to leave those races out where someone died is that there is a "sympathy vote" involved which skews the race Commented Jun 9, 2021 at 12:29
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    I doubt that there is any real "sympathy vote" effect that benefits a different candidate of the same party as the previous, now deceased office holder, although I'd be happy to be proven wrong. Commented Jun 9, 2021 at 16:23
  • I want updates because there are some states with races that were not held in presidential years. Commented Jun 14, 2021 at 14:56
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    @NumberFile I only see one more special election that's occurred since the date of my answer which matches your requirements - New Hampshire State House Merrimack District 23. Happy to update my answer with that; am I missing any?
    – CDJB
    Commented Jul 8, 2021 at 11:37
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    Worth noting that there is bias in the sample, because state legislatures have different size (biasing towards states with large state legislatures like New Hampshire) and because some states don't have state legislative special elections (e.g. in Colorado, state legislative vacancies are filled by political party vacancy committees rather than special elections) biasing results against trends in those states.
    – ohwilleke
    Commented Jul 8, 2021 at 21:19

1 Answer 1


Using Ballotpedia's list of state legislative vacancies for 2020 & 2021, we can identify a total of eight special elections for seats that were contested in the November 2020 general election which were not uncontested and did not proceed to a runoff.

Of these, the average swing was 1.02 percentage points towards the Democratic candidate, while the average swing weighted by the number of votes cast in the special election was 0.096 percentage points towards the Democratic candidate.

Date Seat R Votes Gen D Votes Gen R Votes Special D Votes Special Change Weighted change
02-Mar-21 Connecticut Senate District 27 16594 29279 3109 4692 R+3.68 R+0.45
09-Mar-21 Maine Senate District 14 10189 12998 3136 5247 D+6.53 D+0.86
06-Apr-21 Wisconsin Assembly District 89 22823 10374 8129 4732 D+5.54 D+1.12
06-Apr-21 California Assembly District 79 78367 147994 21332 42476 D+1.19 D+1.19
13-Apr-21 New Hampshire House of Representatives Hillsborough 21 7210 6516 2531 2144 R+1.61 R+0.12
27-Apr-21 Connecticut House of Representatives District 145 1736 5898 225 730 R+0.82 R+0.01
18-May-21 Pennsylvania Senate District 48 18234 9950 23605 10840 R+3.83 R+2.07
08-Jun-21 New Hampshire House of Representatives District Merrimack 23 9610 10844 1393 1912 D+4.84 D+0.25

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