The data suggests what it carefully chooses to suggest.

Here's a list of top 50 cities https://en.wikipedia.org/wiki/List_of_United_States_cities_b... It does not include Baton Rouge, Chula Vista, Chandler, Cincinnati, Cleveland, Fort Wayne, etc.

You can sort of see why - without Chula Vista, Chandler, Stockton, Cleveland, Pittsburgh, Toledo or Raleigh this thesis https://www.crpe.org/examples/six becomes much more muted.

It also measures public schools exclusively, ignoring the fact that urban communities are predominant attractors of private and charter schools - their business model makes less sense in suburbs or rural environment.