Chicago's O'Hare International Airport has reclaimed its title as the world's busiest airport for the first time since 2004.
Mayor Rahm Emanuel made the announcement Wednesday in Chicago during the World Routes 2014 convention, which the mayor's office described as the largest business-to-business aviation event.
According to the Federal Aviation Administration, more than 580,000 flights departed or landed at O'Hare from January to August.
International passenger volume is up 8 percent at O'Hare in the first half of the year, the mayor's office said.
"O'Hare isn't just the busiest airport in the world, it's an asset for the City of Chicago," Emanuel said. "These new gains will help us attract new businesses and solidify our place as the best connected city in the U.S. and around the world."
Representatives of airlines and airports attend the World Routes forum to decide where to fly in the future, according to Emanuel's office. They said some 3,000 people from about 120 countries, 800 airports and 300 airlines are attending.