Per ESPN:

Major League Soccer hopes to push forward with plans to bring a new club to St. Louis as early as 2020, commissioner Don Garber says.

With MLS looking to grow to 28 teams in the near future, Garber met with the chairman of the St. Louis Sports Commission, Dave Peacock, in New York on Thursday to discuss possible expansion to the Missouri city.

And:

MLS, currently at 20 teams, hopes to reach 24 by 2018 with the additions of Atlanta United in 2017, Minnesota United and LAFC in 2018, as well as David Beckham’s Miami franchise.

To get to the stated plan of 28, Garber said that Sacramento, San Diego, San Antonio and Detroit are all under consideration along with St. Louis.

Note that Charlotte and Raleigh aren’t mentioned, which is rather interesting given the recent talk in Charlotte and Raleigh about attracting a MLS team. And given how Charlotte officials view soccer as an economic development opportunity, not being considered is a failure.