File Photo: Inter Miami forward Lionel Messi. AP
But while he said North America would become the "epicenter" of the game with the World Cup, Copa America and FIFA Club World Cup all coming to the region, Garber acknowledged squeezing in all the club and country competitions was a headache.
In his annual "state of the league" address ahead of Saturday's MLS Cup final between Columbus Crew and Los Angeles FC, Garber said MLS was trending upwards in all key areas.
"Lionel Messi had many options for the next chapter of his iconic soccer career. The magnitude of his decision to join MLS cannot be over-stated," Garber said.
"A World Cup champion, an eight-time Ballon d'Or winner is playing in our league. We're not just part of the global conversation of sports but one of the biggest stories in the world, certainly one of the biggest stories this summer," added Garber.
Messi's arrival early in a new 10-year global streaming deal with Apple TV meant "more fans watch MLS games here and around the world than ever before" said Garber, without revealing overall audience figures from Apple.
MLS has also seen rising numbers of fans in stadiums across the country with the derby between Los Angeles FC and Los Angeles Galaxy attracting a league record 82,110 to the Rose Bowl on July 4.
Garber said there had been a record of "nearly 12 million fans" at MLS games throughout the year and also hailed the new Leagues Cup, held jointly with clubs from Mexico's Liga MX, as a "smashing success".
The tournament in the middle of the MLS regular season was won by Messi and Inter Miami and the World Cup-style format won over my skeptics.
"It was a success on every measure and as with so many things this year went on to exceed so many of our expectations. It is only the beginning. This is a tournament which will continue to grow in scale, in scope and reach in the years ahead," he said.
But the addition of Leagues Cup games comes into a calender that will be squeezed by the major tournaments coming to the USA in the coming years.
Next year will see the USA host the Copa America before the new, expanded 32-team, FIFA Club World Cup is held in the country a year ahead of the World Cup itself, co-hosted with Canada and Mexico.
"For the next few years, North America will be the epicenter for the beautiful game," he said.
But with the Leagues Cup, CONCACAF Champions Cup, the US Open Cup as well as the regular season and the playoffs, fitting all the games in while protecting players from burn-out remains a challenge.
Garber said MLS would not stop play during Copa America saying they could not afford to halt their season but would have to be "creative" with their schedule.
MLS usually plays through the regional CONCACAF Gold Cup but Garber said there was no question of the league continuing during the World Cup.
"Clearly the World Cup in 2026 is a different animal, I can't imagine we are going to be playing games during that, but the economic impact of that is significant," he said.
Garber said the big picture may require some changes to how the MLS season is organised and hinted that "Apertura and Clausura" system, used in some South and Central American countries along with Mexico, where the season is split into two separate halves, could be one option.
Garber also said MLS was talking to US Soccer about how to improve the knockout US Open Cup.
"That process is ongoing and there might be changes to our participation sometime in the future, there is nothing we can announce right now," he said.
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