Many would-be voters’ first attempts were foiled by problems at polling places. There isn’t good data on how many people ultimately don’t cast a ballot.

Melanie Taylor arrived at her polling place in a Charleston, South Carolina, church at 7:30 a.m., only to find more than 100 people in line ahead of her. Some of them had already been waiting since 6:15. The voting site was using a computerized login for the first time, and the system was down.

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After 45 minutes, with the line still out the door, Taylor had to give up and leave for work. (She leads a social work program.) She’s planning to try again later and has been monitoring the wait times through a neighborhood Facebook group. The news was not encouraging.

“It felt like a type of disenfranchisement, even though there wasn’t any violation of voting rights,” Taylor said. “The wait has been all day three hours or more, which is ridiculous.”

Across the country, Americans like Taylor have had their enthusiasm to vote tested by problems at polling places. There have been long lines owing to surging turnout, a shortage of voting machines, a shortage of ballots or computer malfunctions. Some voters said they stuck it out for as long as five hours.

But not everyone has five hours. An estimated 500,000 eligible voters didn’t cast a ballot in 2012 because of polling place problems such as long lines, according to the Voting and Registration Supplement of the Current Population Survey. The longer the lines, the more likely people are to give up, one study found, especially in areas with more minority voters. There isn’t good data on what happens to people who leave the line, even if they intend to try again later, according to Charles Stewart, a political science professor at MIT who studies elections.

There’s only a bit more research on the impact of long lines. Voters who have to wait may be less likely to vote in future elections, according to research by Stephen Pettigrew of the University of Pennsylvania. And survey results show people who waited in long lines were less confident that their votes counted. “There’s a bigger hit to confidence than to turnout,” Stewart said.

Sometimes the impediments don’t feel innocent. Brian Wisner showed up at his polling place in Wheaton, Illinois, at dawn, excited to cast his ballot for the Democratic challenger in a toss-up congressional race. Voting was supposed to open at 6 a.m., but it couldn’t start without an election judge from the Republican Party. By the time the Republican judge arrived, at close to 7, Wisner had to leave for work, unable to cast his ballot. “I didn’t have time to vote because I wouldn’t wait it out,” he said. He said he’s planning to return in the afternoon.

The county Republican Party didn’t answer requests for comment. The DuPage County Election Commission said it would hold the affected site open until 7:30 p.m.

“I did hear some people left and didn’t get the opportunity to vote, which is very problematic out here in DuPage County,” said Bob Peickert, the chairman of the local Democratic Party. “It has been nothing but chaos out here since 6 o’clock.”

Some hassles are inevitable with more than 8,000 jurisdictions organizing elections today, especially with higher-than-usual midterm turnout. In Indiana, problems with electronic poll books delayed voting in Johnson County, and Monroe County ran out of ballots, according to local news reports. In Chesterfield County, Virginia, the sole voting machine at a poll site needed to be repaired, and the parking lot was full because the school where the voting occurred had a parent-teacher day, according to Jim Groves, a volunteer. “I saw dozens of people leave,” Groves said. “It’s a mess.”

Lucinda Walters said she was unable to vote in greater Phoenix before work this morning because both of the voting machines weren’t working and her precinct had run out of paper ballots. When she tried again after work, she heard her polling place still didn’t have enough ballots, so she planned to go to another location, which might mean casting a provisional ballot. “Determined to vote,” she said in a text message. “I am a white suburban woman/independent voter that the strategists keep saying will be key to this election.”

Ann Harrison has voted at the First Presbyterian Church in Midtown Atlanta since 1982 and has never had to wait longer than 15 minutes. But today she waited two hours and would have had to wait even longer if poll workers hadn’t waved her ahead to a handicap-accessible booth since she’s 85 years old. The polling place only has three booths, down from a typical six or eight, Harrison said. She counted 85 people in line. “It doesn’t make any sense,” she said.

In 2012, the average voter waited 14 minutes and 2 seconds. One in 10 voters had to wait more than 30 minutes. The 2014 Presidential Commission on Election Administration said no one should have to wait more than 30 minutes.

Lines average twice as long in predominantly minority precincts, according to Pettigrew’s research. He found minorities are three times as likely to wait longer than 30 minutes and six times as likely to wait more than an hour.

C.J. Ogbuehi has voted at the same location in central Atlanta for six or seven years and never had to wait longer than 15 minutes. But today it took him two hours. The site had the usual number of voting machines (10), but Ogbuehi spoke with many other people in line who were transferred from other polling places. “It was chaotic,” he said. “This is exactly what you would expect when close that many location and provide no extra resources. I don’t know if it was designed to be voter suppression, but it smells like it.”

In Chicago, Eric Hellige waited 40 minutes to vote, but when he got to the front of the line, the poll workers said they had run out of one of the ballot’s two pages. He could either wait for refills or come back later. “People were frustrated and annoyed that they had to wait that long just to find out they could not vote,” Hellige said. “I had the luxury of coming back later.”

A few hours later, he sent a text message with an update: “Voted successfully!”