Fairfax County elections officials are bracing for confusion at the polls on Election Day, in part because glitches in Virginia’s voter database could lead some voters to the wrong polling place.

County officials said Monday that they discovered about 2,200 cases in which a state-run computer program assigned voters to incorrect precincts.

Voters were sent new voter ID cards as soon as the errors were discovered, for the most part in September. But at least one error was discovered as recently as last week. New cards were sent by two-day or overnight mail in some cases to make sure they arrived in time.

The problems, which have not been detected in other Northern Virginia jurisdictions, had Fairfax officials worried on the eve of a high-stakes Election Day. Local School Board races have been especially hot, and Republicans need to pick up just two seats to take control of the state Senate.

Elections officials say they think the problems occurred in Fairfax and not elsewhere because the county, with its population density and highly prized swing voters, was sliced and diced more than most during redistricting.

Lolita Mancheno-Smoak, an at-large candidate for the Fairfax school board, greets voters at the Clifton Presbyterian Church. (Gerald Martineau/FOR THE WASHINGTON POST)

“We’ll see how things go tomorrow, but we do have some serious issues,” said Sharon Bulova (D), chairman of the Fairfax County Board of Supervisors. “They’ve had people call up and say: ‘Hey, wait a minute. I got this voting card, but I know where I’m supposed to be. I’m getting campaign literature from these candidates, but my voter card is saying otherwise.’ ”

Redistricting always creates confusion, election officials said, as district lines shift to reflect the latest census figures. Voters who don’t see familiar names on the ballot sometimes think it’s a mistake when, in fact, they’ve simply been moved into a new district.

“Just because they’ve always voted down the street for a certain set of people doesn’t mean that they’re still voting right down the street for the same group of people,” said Cameron Quinn, Fairfax’s general registrar.

But normal, decennial disorientation is only part of the story this year in Fairfax.

“Redistricting is always a challenge,” Quinn said. “It’s complicated this year by the fact that we have a new statewide database and . . . things don’t seem to be working quite properly, but no one’s quite sure why.”

As candidates and Republican and Democratic activists prepared to knock on doors, they saw that voter addresses sometimes didn’t jibe with district maps, Quinn said, and they alerted her office to the problems.

Some absentee voters noticed that the candidates on their ballots did not match the ones who’d knocked on their doors and sent them campaign literature. The board also conducted an audit, which found a handful of additional errors.

County officials are using a four-year-old computer program developed by a private vendor and maintained by the State Board of Elections. Fairfax officials found that when they tried to update the system with new district boundaries, the computer system did not always accept the changes.

“Some of the data entered wouldn’t seem to stick overnight,” Quinn said.

Her staff had to enter the data multiple times and, in some cases, turn to the state board staff for help.

Susan Pollard, spokeswoman for the state board, said that some other jurisdictions had problems with the computer system but that they were resolved sooner than in Fairfax.

“Fairfax has had some issues with new voter information cards and we [the state board] have worked very close with the General Registrar’s office to resolve them,” she said via e-mail. “[R]edistricting is a complex process and it’s reasonable to expect human error can be a factor when taking on such a comprehensive task.”

Quinn urged voters to check precinct maps when they arrive at polling places to make sure their homes lie within the proper boundaries. She also suggested that they review the sample ballot before entering the voting booth. And if they question whether they have the right ballot while voting, she said, ask for help before hitting the vote button.