Kamala D. Harris won San Mateo County with 73.5% of the vote, ahead of Donald J. Trump. 330,510 votes were counted. The party margin was a Democratic lead of 50.3 points. Compared with the previous presidential election in San Mateo County that is loaded, the margin moved 7.4 points toward Republicans.
San Mateo County leans Democratic by 53.7 points compared with the nation (our partisan lean index, based on president 2024 75% + 2020 25%).
San Mateo County voted for the winner of the national popular vote in 5 of 7 presidential elections from 2000 to 2024. On average its margin sat 47.2 points away from the national margin.
In 2024, 330,510 votes were cast in the biggest race, which is 66.8% of the 495,020 citizens aged 18 and over in San Mateo County.
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