Opponents of a proposition that would make a small suburb of Seattle home to the highest minimum wage in the country will seek a recount after the measure passed by just 77 votes.

The measure would mandate a $15 minimum hourly wage for workers at Seattle-Tacoma International Airport. On Tuesday, King County elections officials certified results that show the measure passed by just over 1 percentage point, 3,040 votes to 2,963.

Tiny SeaTac is home to just 12,106 registered voters. But proponents and opponents spent more than $2 million — about $165 per registered voter and $327 for every voter who actually cast a ballot — fighting over the initiative.

Labor unions and their backers spent more than $1.4 million campaigning for the wage increase, according to filings made with the state Public Disclosure Commission. Several branches of the Service Employees union contributed more than $325,000 to the effort, while Working Washington, a coalition of labor groups, chipped in another $150,000 and the Teamsters union added $55,000.

Alaska Airlines, which is headquartered in Seattle and uses SeaTac as its major hub, spent more than $155,000 to oppose the measure. The American Car Rental Association gave $100,000, while a political action committee run by the state hotel and lodging association spent $109,000 against it. The Washington Restaurant Association, whose members would have to pay their employees at SeaTac under the new wage, also chipped in $60,000 against the measure.

Opponents said they would seek a recount, which will cost them 25 cents per ballot.

“When an election is this close, everyone should be assured the outcome is as certain as possible,” Scott Ostrander, co-chairman of Common Sense SeaTac, the group that led the opposition, said in a statement. “We are asking for a hand count of the ballots to get the most accurate possible count.”

Proponents blasted Alaska Airlines and other business interests, which have gone to court to stop the wage hike.

“We’re not surprised they’ve asked for a recount. The cost of the recount is less than the price of some of the tickets sold to fly these airlines,” said David Rolf, president of SEIU Healthcare 775NW. “We don’t believe it will delay the inevitable.”

Recounts can change election results in Washington State. In 2004, Republican Dino Rossi finished ahead of Democrat Christine Gregoire in the race for governor, by a margin of just 261 votes. But a recount gave Gregoire a lead of just 129 votes. Still, the flip of about 400 votes out of more than 2.7 million cast is a much smaller change than the number of votes that would have to be tossed or changed in SeaTac.

Washington conducts elections entirely by mail, meaning it usually takes the state several weeks to finalize election results. Though King County officials certified their results this week, final numbers won’t be certified until next week, when Secretary of State Kim Wyman (R) and Gov. Jay Inslee (D) give their sign-off.