ATLANTA — The typical flier might wonder why an airport would promote its designation as the world’s busiest. Images of long lines, crowded concourses and auxiliary parking lots in the next area code could be evoked.

But it is no small matter at Hartsfield-Jackson Atlanta International Airport, where officials say that the vibrancy of the local economy rests in part on how many passengers course through its sprawling terminals every day.

And it is why some of those authorities took notice recently that Chicago’s O’Hare International surpassed Hartsfield-Jackson in one measurement of an airport’s activity: takeoffs and landings.

Soon after, Atlanta’s mayor, Kasim Reed, announced that he was gathering a dozen marketing experts from prominent local firms and civic organizations to figure out how to keep its airport — and the area’s fiscal fitness — thriving.