Correction: An earlier version of this story incorrectly identified the date for this year’s general election. It will be Nov. 6. This version has been updated.

Candidate Libby Garvey, left, greets a voter outside a polling place March 27 during the special election for an open county board seat. (Bill O'Leary/THE WASHINGTON POST)

Democrat Libby Garvey won a three-way race for a vacant Arlington County Board seat Tuesday in a special election that set a record for low turnout at just under 12 percent.

Garvey bested Republican Mark Kelly with 7,007 to 6,194 votes, while Green Party candidate Audrey Clement trailed with 1,007.

“Oh, it was a nail biter,” Garvey said. “This was a special election and we didn’t have a big turnout, but I’m delighted to have the confidence of the voters.”

Kelly, who won 15 of the 53 precincts as well as the absentee vote, took pride in keeping Garvey at 49.1 percent in the heavily Democratic county, where the County Board has been all-Democrat since 2000.

“I’m certainly disappointed we didn’t get over the top,” he said. “I think we convinced enough people that if they come out in a special election . . . a Republican with the right message can certainly win.”

The extremely low turnout alarmed candidates and activists early in the day, when a mid-morning estimate that only 2 to 3 percent of voters had arrived at the polls. Even the 14,252 who ultimately showed up set a modern record low for a special election — by about 5,000 votes — and those are routinely less attractive to voters than regular elections.

“There’s been some speculation that it’s election fatigue,” said Linda Lindberg, Arlington’s general registrar, who runs the elections office. A primary election in August was followed by the November general election, then a Democratic county caucus in January and a Republican presidential primary in March. And county voters are not finished for the year: There’s a June 12 primary for U.S. Senate and U.S. House seats and possibly one for the County Board, and a Nov. 6 general election for Congress, the County Board and School Board.

Clement, the Green Party candidate, called the low turnout “pathetic.”

“I do believe I got my message out through the media . . . but low turnout does not favor insurgents of any party,” she said.

Tuesday’s election was to fill the eight months left in the term of Barbara Favola, who was elected last fall to the state Senate. Garvey will have to stand for reelection in November. But she planned to waste none of the eight months, saying she wants to be sworn in at 5 p.m. Wednesday.

The campaign was compressed into eight weeks after the Democrats chose their candidate Jan. 21 from a field of five contenders. Kelly was the only Republican to run, and Clement was the only Green.

All three candidates were known to Arlington voters from previous campaigns. Garvey, in addition to her 15 years on the School Board, lost a primary race for a state Senate seat last summer. Clement came in third in a race for two County Board seats in November against now-Chairman Mary Hynes and now-Vice Chairman J. Walter Tejada, and Kelly lost a 2010 County Board race against board member Chris Zimmerman.

Garvey raised almost twice as much campaign money as Kelly overall but was matched by him since Jan. 1. She worried from the start about a low turnout, cautioning her supporters that the last two elections lost by Democrats were special elections. “Ninety-three hundred Republicans always seem to turn out,” she warned, “but the Democratic turnout varies.”

Angela Thompson, a teacher at Glebe Elementary School, didn’t realize an election was underway Tuesday until she arrived at work, which was serving as a polling station. Another woman, who voted at the Madison Community Center, said it took an automated phone call to alert her to the election. “Robo-calling works!” she said, declaring that she had voted for “Libby Whatever-Her-Name-Is.”