MLS intends to eventually expand to 30 teams, with teams 29 and 30 requiring a $200 million expansion fee. St. Louis and Sacramento are being eyed towards teams 28 and 29.
MLS currently has 24 teams, with Nashville, Austin, and Miami set to join.
"In the last 10 years we've been experiencing unprecedented growth for a major league in North America. Expansion has been a key driver of that growth, and it really is a great measure of the enormous enthusiasm and the commitment that our fans have in markets both new and old to support our league and our players and to see the sport grow," said MLS commissioner Don Garber.