Mapping the 2018 San Francisco Mayor's Race

By Pedro Hernandez and Theodore Landsman

This graphic maps the performance of San Francisco Mayor London Breed, and candidates Mark Leno and Jane Kim in the 2018 special Mayor's race by precinct. No other candidate captured a plurality of the vote in any round or any precinct, but totals for the remaining candidates are available below.



Candidate Round 1 Round 2 Round 3 Round 4 Round 5 Round 6 Round 7
London Breed 92121 92243 92442 93605 96392 102767 115977
Mark Leno 61416 61533 61881 62861 64128 68707 113431
Jane Kim 60738 60829 61422 61843 63261 66043
Angela Alioto 17552 17737 17929 19626 21981
Ellen Lee Zhou 9576 9687 9829 10637
Richie Greenberg 7051 7128 7242
Amy Farah Weiss 1675 1735
Michelle Bravo 900


This is a follow up to our previous reporting on the 2018 San Francisco Mayoral Election.

The San Francisco Department of Elections releases several detailed files of public data on ranked choice voting (RCV) contests. These files include a Summary Report, a Statement of Vote, Ranked Choice Voting Results Table, and well as a Ranked-Choice Voting Ballot Image file. This ballot image file contains an anonymized record of ballots cast, which many researchers use to study the effect of RCV as an electoral reform. The public has access to these files, and some have already audited the accuracy of the count. 

However, many initial reports of the mayoral election only reported the first-choice accounting of the election, as reported in the Statement of Vote. Such reporting offers only a snapshot of how the candidates fared in the first round of the RCV contest. Here, using ballot image information, we dive deeper into the final round count by district and precinct. 

Click here to access a google sheet document of final round district and precinct information. 

Final Round By Districts

In terms of districts, London Breed did win a majority of districts: Six. 

Breed won in Districts 2, 4, 6, 7, 10, and 11. Leno won in Districts 1, 3, 5, 8, and 9.

District 10 offered Breed the largest margin of victory over Leno where she led Leno by 3,985 votes in the final round. 

Board of Supervisors District Breed Final Round Vote Leno Final Round Vote  Winner 
1 9,929 10,143 Leno
2 12,635 9,435 Breed
3 7,949 8,674 Leno
4 10,055 8,485 Breed
5 13,454 13,690 Leno
6 8,141 7,473 Breed
7 12,844 10,459 Breed
8 14,229 20,012 Leno
9 8,560 12,099 Leno
10 10,115 6,130 Breed
11 8,066 6,831 Breed
Total 115,977 113,431 Breed


However, the biggest surprise is that Mark Leno narrowly won in District 5, which is Mayor London Breed's supervisorial district. Initially, Breed received 11,270 of first choice support in District 5, followed by Jane Kim who received 8,101 first choice votes. Mark Leno came in third with 6,908 first choice votes in the District. When Jane Kim was eliminated in the city-wide RCV count, Leno picked up 6,782 votes from supporters of Jane Kim and other defeated candidates. Leno then led with 13,690 votes to Breed's 13,454. 

In District 8 delivered the biggest margin vote to Leno. Initially, Leno he led with 12,731 first choice votes, he then picked up 7,281 additional votes from supporters of other candidates, mainly Jane Kim. Of Jane Kim’s 8,232 votes in District 8, 84% of those ballots who indicated another preference went to Mark Leno in the final round. Leaving Leno with  20,012 votes in District 8. 

Final Round By Precinct

Overall, London Breed won 320 out of 596 precincts, Mark Leno won 271, and five precincts were tied. Breed fared well across the city and gained deep support from west side, Western Addition, Marina, and Bay View/Hunters Point voters. Not suprising, in every single precinct where Jane Kim led, those precincts all favored Mark Leno in the final round.

Those who follow elections closely may note that there are 604 precincts in San Francisco. However, some of these precincts had no votes cast, and most of these no-vote precincts are public parks. 

Additional Maps

First Choice Support for London Breed

First Choice Support for Mark Leno

First Choice Support for Jane Kim

Final Round Breed v. Leno

Additional Resources

San Francisco Report: RCV is Working as Intended with Positive Voter Experience and Increase in Voter Turnout and Use of Rankings

Exhausted Ballots in the 2018 San Francisco Mayoral Election