Final figures show 46.6 percent of San Francisco voters turned out for the March 5 election, the lowest for a primary since 2012.
A total of 233,465 ballots were cast in a city with 500,856 registered voters, the San Francisco Department of Elections certified Friday.
President Joe Biden won 89.9 percent of 166,816 Democratic votes.
Republicans cast 19,175 ballots, with former President Donald Trump winning 62.6 percent. Former U.N. Ambassador Nikki Haley received 35.5 percent, while Florida Gov. Ron DeSantis got 2.9 percent.
In the 2008 primary election, turnout was 64.7%, according to elections department records. The primaries that year were won by Democrat Hillary Clinton and Republican John McCain.
The lowest previous presidential primary turnout was 30.8 percent in 2012, when the party flag-bearers were Barack Obama and Mitt Romney.
Almost nine out of 10 ballots this year were vote-by-mail; 27,929 people cast ballots in person on Election Day, the department said. In previous primary years, turnout was 42.5 percent in 2004, 56.5 percent in 2016 and 60.5 percent in 2020.