"That's a strong statement about the league and the growth of the sport in the United States and Canada," MLS Commissioner Don Garber said in a statement.
A committee and Garber will review applications and conduct in-person meetings with potential owners and officials from prospective markets during the first half of 2017.
The applicants submitted documentation that focused on a description of ownership structure and financial information, details on a proposed stadium site, financial projections and commitment letters for stadium naming rights.
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MLS said two of the four new teams will be announced by the end of 2017 and begin play in 2020. The other two teams will be announced at a later date with a more specific timeline decided later this year.
With the addition of Atlanta United and Minnesota United FC, MLS will have 22 clubs competing during the 2017 season.
The Los Angeles Football Club will join the league in 2018 while MLS said it is making progress with plans for an expansion team in Miami, which would bring MLS to 24 clubs.
(Reporting by Frank Pingue in Toronto; Editing by Andrew Both)
