Major League Soccer is aiming to add four new teams to become a league of 24 by 2020.

Commissioner Don Garber, making one of his stately appearances on the ESPN half-time show at the MLS All-Star game, had promised some sort of announcement, but nobody quite expected it to be setting the timescale and odds for the next stage of MLS expansion. But there he was announcing that the league wanted to expand by four teams for the 2020 season — officially putting those already in the game and those toying with entering it, on notice that the chase was on.

No new team entered the league this year, after years of increasingly confident expansion that had followed the setback of contraction in 2002. The slowdown was due to the desire to close on a stadium and a franchise holder for a second New York team and a wealth of human and financial resources had been spent on that in the last couple of years, coupled with the Commissioner's statements that the 20th expansion team would be NY2, in whatever form or location that might take. Other cities kept making noise about expansion, insisting they were better prepared and more deserving than a second franchise in a media market where the existing team was struggling for attention. But MLS pressed ahead in the belief that a second New York team was key to their strategy.

The entry of Manchester City (and the Yankees) into the conversation allowed MLS to finally announce New York City FC as the second New York team earlier this summer - scheduled to enter the league in 2015. No matter that the stadium deal in Flushing, once seen as a prerequisite for a franchise to be awarded, would soon stall in the morass of New York politics, a "Mission Accomplished" banner of sorts could now be hung above the New York project and the talk could again turn to expansion.

But that conversation still felt a way away until the Commissioner's announcement. New York City FC will be the 20th MLS team and the league had indicated there may be a hiatus when it reached that symbolic number. Conversations with interested would-be owners would continue, it was assumed, but without a definitive target or timescale. Those conversations become more charged now.

So who's in the running? Well, there are a few territories currently underserved where a team would make sense, and where there is already some groundswell of support:

The South

The long time presumptive frontrunner has been Orlando City, the USL Pro side who at various stages in the last year or so have seemed tantalizingly close to closing the stadium deal that would make them a strong favorite for an MLS slot. Though as the New York City FC deal shows, the stadium being in place, once considered a non-negotiable cornerstone of any credible bid, is perhaps not such a definitive requirement as it once was. If Orlando could secure the approval in principle of MLS, the numbers might make a bit more sense to the State legislature which is where the most recent public/private stadium proposal foundered.

And then of course there's Miami and David Beckham, who has the right to purchase an MLS franchise at a reduced price, based on a clause in his initial contract with the league. Whether even the star power of Beckham would be enough to make a notoriously fickle sports market take a team to their hearts is another matter — it may take someone of his star presence to sustain interest even when the first flush of enthusiasm has gone. Commissioner Garber is prone to speak of the "ghost of the former NASL haunting the corridors of MLS". Never mind NASL, the ghost of MLS failures past still haunts Florida. Could Beckham succeed where Miami Fusion had failed? He's certainly looking into it, and has taken exploratory meetings in the city.

And then there's Atlanta, home of the Silverbacks, and perhaps most importantly a name that has cropped up more than once out of the mouth of the commissioner when discussing possible expansion teams, not least because it's the largest television market without an MLS franchise.

Further North, but connected to the stretch of America conspicuous for its lack of MLS teams, there's another possibility of putting a team in the Carolinas, perhaps even bringing up Carolina Railhawks to MLS.

The Midwest

It wouldn't take a lot to make another underserved area of the country grow more potential marketable rivalries, if a viable owner could be found in St Louis. Sporting Kansas City and Chicago Fire would have a new natural rival, and a town with a decent soccer past could have a solid soccer future. The City has come close before, even having a stadium agreed, but MLS were not convinced by the range of backers that the last serious contender Jeff Cooper had on hand and the partners decided against proceeding. Sometimes having a location that ticks a lot of boxes is not enough.

Elsewhere, Indianapolis is about to launch an NASL side whose founding fan-friendly principles may have them in a strong position sooner rather than later, though the involvement of MLS 1.0 fan-friendly exec Peter Wilt may hinder as much as help. And Andreas Apostolopoulos's Triple Group continue to make noises about a stadium in Detroit, either as part of the Pontiac Silverdome complex or a more city-based location. In the meantime the NPSL Detroit City fans continue to punch above their weight in terms of crowds, and could yet form the mainstay of a future bid, if that trend continues.

A little further West is the prospect of a tie in with the Minnesota Vikings, particularly in the wake of the Minnesota legislature approving a new NFL stadium with provision for an MLS franchise, last year. The stadium is scheduled to open in 2016.

The West

Here's where we're getting slightly into wild card territory. Sacramento has quietly gone about making itself a viable contender by founding a USL Pro team and identifying a suburb called Elk Grove as a possible home for a stadium. San Antonio, Texas is another possibility — the Scorpions NASL team has been a successful launch and they have a neat scaleable stadium that currently holds 8000, but can be expanded to 18,000. And again, senior MLS figures have been quoted as saying the league is looking seriously in Texas.

And then as the joker we have the beleaguered Chivas USA. Chivas is facing an ugly employment court case, and immediately after his expansion announcement on ESPN, the Commissioner had to endure a reasonably intense cross-examination about whether the club discriminated against non-Hispanic players and staff. Whenever the conversation comes up about how badly or indifferently certain franchises are run, Chivas is one of the teams that comes up frequently. At times recently there's been something of a suggestion that Chivas should be moved and rebranded, given how much they are struggling compared to their StubHub Center neighbors, the Galaxy. If that were to happen that could muddy the waters in any of the four new potential markets, depending on the parameters for such a move.

So take your pick of any four from that little lot, add in Ottawa or just speculate on the New York model of a second franchise. Sporting player Matt Besler was doing just that in the wake of the All-Stars' Roma defeat — upon being told of the expansion news he joked "Kansas City 2!". "Not gonna happen" growled his All-Star and club coach Peter Vermes beside him. Some cities aren't big enough for two — while some cities will have watched Roma play in the beautiful, modern stadium at Sporting Park in front of a packed and engaged crowd, heard the Commissioner's plans, and dared to believe that they might become one of four.