How did Miami end up with the best airport in the country for transit?

Miami International Airport leads the nation in transit options, according to a new ranking that gives credit to the number of bus routes running from the busy travel hub to diverse destinations.

“It certainly doesn’t hurt that it’s fairly centrally located within the city itself,” mobility start-up Transit Screen said of MIA, which actually sits on the outskirts of Miami. “But the real difference? The humble bus.”

Transit Screen, a Washington, D.C., company that sells technology aimed at synthesizing various transportation schedules, said MIA fares well in the traditional connectivity measure of rail. In 2012, Miami-Dade opened a three-mile extension that linked the airport to Metrorail, the lone extra station built with the half-percent sales tax that voters approved 10 years earlier under the false promise of an historic rail expansion.

But while other major cities match MIA in terms of rail access, the Miami airport distinguishes itself by offering direct bus routes beyond downtown, according to Transit Screen. At the Miami Intermodal Center — the transit hub connected to MIA by the automated railway known as the MIA Mover — nine bus routes can take passengers to Miami Gardens, Miami Beach, the Dolphin Mall, the Blue Lagoon office district and other popular spots.

The intermodal center “includes nine bus lines that run through it fairly consistently and serve many neighborhoods, increasing access versus [other] airports like Denver or Dallas where transit mostly serves to carry travelers downtown,” Transit Screen wrote in a release announcing its rankings.

MIA finished first on the list, followed by O’Hare in Chicago, and the airports in Minneapolis-St. Paul, Minnesota; Boston’s Logan; and Philadelphia. The rankings were limited to the 20 busiest airports in the country.