Commissioner Don Garber made the announcement Thursday at the league's Board Of Governors meeting in Los Angeles.
The league is currently at 24 teams, with FC Cincinnati joining the league this season. Nashville and Miami are teed up to start next year and Austin will come aboard in 2021.
The board did not identify markets but groups in Sacramento and St. Louis will be invited to give formal presentations to the league's expansion committee. A decision will be made in the coming months.
It has not been determined when the new teams will join the league.