By the time the polls open on the final day of the presidential election, nearly a million San Diego County residents will have already voted, and thousands more will fan out to vote centers, post offices and ballot drop boxes Tuesday to cast votes for president, Senate and dozens of ballot measures and local offices. In addition to the highest-profile race, local voters will also be deciding the fate of 10 statewide ballot measures, a countywide half-cent transportation sales tax increase and a slew of legislative races and local measures, depending on where they live. More than 200 vote centers across the county are open until 8 p.m., including six so-called super centers equipped with extra check-in stations, voting booths and poll workers. Voters can also drop their ballots in the mail or in one of more than 150 official drop boxes by 8 p.m. Tuesday. Voting by mail remains the overwhelming choice for San Diego County voters. County election officials had received more than 880,000 mail-in ballots, while around 80,000 people had voted in person by Tuesday morning.   And by the time every vote has been counted, officials expect turnout of between 80% and 84% — in line with past presidential elections. The 2016 presidential election saw 81% turnout, and 2020 had nearly 84%, reports show. Those who choose to vote in person should expect long lines, election officials say. And with so many contests on the ballot, it might take longer than usual. As the sun set on Monday, a handful of voters who’d come straight from work filed into the polling center at the Mission Valley Library just before it closed for the evening. “Chances are tomorrow is going to be a madhouse, so I wanted to get this out of the way tonight,” Samantha Austin said. Not everyone made it in time. Dressed in his Navy uniform, Phillip Quinn said he had sat down at a table in the library to fill out his ballot after realizing he had arrived 15 minutes too late to vote in person there. “It really doesn’t matter how I do it,” Quinn said, as he dropped his completed ballot into the drop box outside the library. “I just knew I needed to make sure I voted.” People drop off their ballots at the San Diego Registrar of Voters before Election Day on Monday, Nov. 4, 2024 in San Diego. (Ana Ramirez / The San Diego Union-Tribune) On Election Day, a small but steady stream of people were arriving to cast their ballots at the Registrar of Voters office in Kearny Mesa after polls opened at 7 a.m. Carl Savoia of San Diego was one of them. He said his vote “feels more important than previous elections. There are two drastically different platforms. This is more significant than previous elections.” Registrar of Voters Cynthia Paes said no issues were reported as polls opened Tuesday. “Operations have been running smoothly. All of our voting centers opened on time at 7 a.m.,” she said. “They are ready to serve voters.” A steady stream of voters were seen dropping off ballots Tuesday morning at a drop box at the entrance to Balboa Park near Sixth Avenue and Laurel Street. “I have a teenage daughter so the decisions we make today will impact her,” said Michelle Sainz of Chula Vista, who described herself as someone who votes regularly. “I want to make sure what we do today is of benefit not just to us, but to future generations.” County officials recommend voters read their voter information pamphlet and mark their selections on their sample ballot in advance so they can refer to their choices once inside the voting booth at the vote center. Eligible residents who want to vote but aren’t yet registered can still conditionally register and vote in person. Voters returning their ballot by mail should remember to sign and date the envelope to ensure their vote will count. They can track it by signing up for “Where’s My Ballot?” at california.ballottrax.net. Voters can check their registration status or locate vote centers and ballot drop boxes online at sdvote.com. They can also call 858-565-5800 or 800-696-0136 for information. Although the polls close Tuesday evening, full election results will take much longer. The county Registrar of Voters will begin to release partial results — from ballots received by Monday — soon after the polls close at 8 p.m. They’ll update the results throughout the night and in the following days as more ballots are counted, but the official results will not be certified until early December. Kalli Legakes Adams, 31, of San Diego, prepares to vote at the San Diego Registrar of Voters before Election Day on Monday, Nov. 4, 2024 in San Diego. (Ana Ramirez / The San Diego Union-Tribune) The presidential race has riveted most voters’ attention, along with control of the two chambers of Congress. But down the ballot, San Diego County voters are also deciding six contested state Assembly seats, one state Senate seat, 10 state propositions and scores of local races — along with five seats in the U.S. House of Representatives and California’s open seat in the U.S. Senate. One highlight among those is the race for the 49th Congressional District. Republican Matt Gunderson is hoping to unseat three-term Democrat Mike Levin for the coastal North County and southern Orange County seat. At the county level, the high-profile race in District 3 — where former San Diego Mayor Kevin Faulconer is challenging incumbent Supervisor Terra Lawson-Remer — could determine which party controls the Board of Supervisors. In the city of San Diego, voters citywide will decide not only whether to re-elect Mayor Todd Gloria but also who will succeed the termed-out city attorney, among other races. Voters in at least a dozen other cities will also be deciding who will represent them and whether to approve local measures. In state legislative races, the 75th and 79th Assembly districts both feature runoffs between two candidates from the same party. Republican activist Carl DeMaio and party-backed rival Andrew Hayes are running to represent a wide swath of East County and inland North County in Sacramento, while fellow Democrats Colin Parent and LaShae Sharp-Collins are competing to represent portions of eastern San Diego, Lemon Grove and La Mesa. Consult the The San Diego Union-Tribune’s voter guide online at sandiegouniontribune.com/election-2024-san-diego-county-voter-guide to learn more about the people and items on your ballot. Staff Writer Rob Nikolewski contributed to this report.