Maya Buffett-Davis, 23, said she arrived at the museum at 6 p.m. after a full day of classes at the University of California, Los Angeles. She is from Berkeley, and had registered to vote as a Los Angeles resident several weeks ago.
But when she got to the front of the line after four hours of waiting, the check-in system did not turn up any combination of her name. Re-registering her took an extra five minutes.
Ms. Buffett-Davis, who is studying fine arts and gender studies, said she saw someone else in the voting area report four straight paper jams, which she said sounded almost unfathomable considering how simple the ballot machines looked.
She stayed to vote because “I believe in this,” she said. “I believe in peace, and peace is when all voices can be heard. That’s not what our voting system is, but that’s what it can look like.”
Word that The Associated Press had called the race for Mr. Sanders promptly at 8 p.m. spread quickly through the line.
Neither that announcement nor the already two-hour wait would deter Mark Hansen, 42, from staying as long as it took to tap the screen for Elizabeth Warren.
“It’s still complicated here because of the congressional delegates, and meeting the 15 percent threshold can make a difference,” he said. “Even if they call a winner, it still matters.”
Mr. Hansen, an instructor at U.C.L.A., said he would have brought a book if he had known how long the wait would be. “I have a lot of regrets,” he said.
“I know that they don’t call things until polls close, but even if polls close that doesn’t mean that people aren’t still in line still to vote,” he added. “I think that’s a problem.”
“I’m almost there, and it’s almost Wednesday,” said one voter close to the check-in station.
As the person in front of her left the line and headed home, Shetarrah Byfield said she had been waiting for two and a half hours. Ms. Byfield was buoyed by the sight of so many people staying late. “I’m inspired, but tired,” she said. “But more inspired than tired.”
A student at Santa Monica College, she was passing the time in line by checking in on the Democratic grass-roots nonprofit where she is a fellow and organizer.
“Every vote matters right now,” Ms. Byfield, 24, said. “Even if California was called early on people still need to vote. Even though it’s such a hassle, and it’s tiring, it’s showing a shift in people’s beliefs in views. A shift in wanting change to happen.”
She said her friend ahead of her in line had planned on voting for Ms. Warren, but when she heard about Joseph R. Biden Jr.’s victories in other states on Tuesday, she changed her vote to support the former vice president.