NASHVILLE — Major League Soccer Commissioner Don Garber was having a moment.

On a sunny morning in mid-July, Garber arrived in Nashville to meet with politicians, business leaders and sports executives eager to bring an M.L.S. team to the city. The two-day fact-finding mission was part of a 12-city tour being conducted by Garber and his deputy, Mark Abbott, to determine which of the dozen cities will be chosen as home to the two expansion teams M.L.S. plans to approve this year.

Already Garber had been greeted by a marching band in Cincinnati and by fans waving giant cardboard cutouts of his face in Sacramento.

So for Garber, who stood at the lectern in Nashville, the latest warm reception seemed as much a validation as an opportunity. He had taken over a struggling 12-team league in 1999 and contracted it to 10 clubs two years later to stave off its collapse. Now, the league is executing a plan to grow to 28 clubs by 2020, and interest in professional soccer in the United States — in M.L.S. and far beyond it — has surged.

Instead of seeing teams fold or move, the league has investors ready to spend hundreds of millions of dollars on expansion fees and stadium construction. The new stadiums, the new sponsors, the new players emerging from the league’s new academy programs “empower anyone running a sports league,” Garber said.