Problem signs that arose during weeks of early voting carried into Election Day as some voters across the country faced hours-long lines, malfunctioning voting equipment and unexpectedly closed polling places.
Some of the biggest backups were in Georgia, where the governor's race was among the nation's most-watched midterm contests and was generating heavy turnout.
One voter in Gwinnett County, Ontaria Woods, waited more than three hours and said she saw about two dozen people who had come to vote leave because of the lines.
"We've been trying to tell them to wait, but people have children. People are getting hungry. People are tired," Woods said.
The good government group Common Cause blamed high turnout combined with too few voting machines, ballots and workers.
Fulton County elections director Richard Barron acknowledged that some precincts did have lines of voters but said that was due to the length of the ballots and voting machines taken from use because of an ongoing lawsuit.
While voting went on without hitch in many communities, voters from New York to Arizona faced long lines and malfunctioning equipment.
Across New York City, reports of broken ballot scanners surfaced at several polling places. Turnout was so heavy at one packed precinct on Manhattan's Upper West Side that the line to scan ballots stretched around a junior high school gym. Poll workers there told voters that two of the roughly half-dozen scanners were malfunctioning and repairs were underway.
Voters arriving at two separate polling stations discovered that most scanners had broken down, forcing some people to drop their ballots in "emergency ballot boxes" or vote using an affidavit ballot.
"There are broken scanners everywhere in Brooklyn," Stefan Ringel, spokesman for Brooklyn Borough President Eric Adams, told the AP.
He said Adams and his staff are being flooded with phone calls, emails and text messages reporting breakdowns in more than a dozen neighborhoods.
Compared to the 2016 elections, he said, "anecdotally, it seems worse, and there's confusion among poll workers about what to do."
Many voters nevertheless stuck it out, determined to cast their ballot.
"People are grumpy and frustrated but positive in a weird way, making jokes and talking to one another. I think it's because we all are in the 'no one will stop our vote today' mood,'" said Nikki Euell, an advertising producer who waited more than two hours to vote in Brooklyn's Greenpoint neighborhood.
The local breakdowns are a symptom of a larger problem with the nation's voting infrastructure, said Lawrence Norden, a voting technology expert with the Brennan Center.
More than 40 states use computerized voting machines that are more than a decade old or are no longer manufactured.
"It's further evidence, if any was needed, that it's long past time to modernize our voting infrastructure," Norden said. "Voters have a right to be frustrated by long lines. And they have a right to expect voting machines that work and have a paper backup."
Elsewhere, polling place confusion caused problems for voters and poll workers.
In Phoenix, a polling site was foreclosed on overnight. The owners of the property locked the doors, taking election officials by surprise. Voters had been sent to another precinct nearby, but Maricopa County Recorder Adrian Fontes tweeted that the location in Chandler was up and running shortly after 7 a.m. Tuesday.
For about an hour after polls opened Tuesday morning, a Sarasota County, Florida, precinct had to tell voters to come back later because their ballots were not available.
In one Indiana county, voting was snarled for hours because of what election officials say were computer problems checking in voters while in another part of the state a judge ordered 12 polling places in a northwestern Indiana county to stay open late after voting didn't start as scheduled.
In Texas, home of a hotly contested U.S. Senate race, delays were reported in Houston after apparent issues with registration check-in machines at some polling places.
And in El Paso, the U.S. Border Patrol canceled a "crowd control exercise" that was scheduled for Tuesday, following criticism from civil liberties groups that it could dissuade people from voting.
Border Patrol agent Fidel Baca confirmed Tuesday that the exercise in a Latino neighborhood of El Paso was canceled, but declined to say why. The Texas Civil Rights Project says the exercise, billed by the Border Patrol as a "mobile field force demonstration," was to be held within a half-mile of a polling site.
Tuesday's election marks the first nationwide voting since Russia targeted state election systems in the 2016 presidential race. Federal, state and local officials have been working to make the nation's myriad election systems more secure. They have beefed up their cybersecurity protections and improved communications and intelligence-sharing.
There have been no signs so far that Russia or any other foreign actor has tried to launch cyberattacks against voting systems in any state, according to federal authorities. There was also no indication that any systems have been compromised that would prevent voting, change vote counts, or disrupt the ability to tally votes, U.S. officials said.