The U.S. cities with flights to Cuba will be Miami; Fort Lauderdale, Florida; Chicago; Philadelphia and Minneapolis, according to DOT. The airlines are: American Airlines Group Inc., Frontier Airlines Holdings Inc., JetBlue Airways Corp., Silver Airways Corp., Southwest Airlines Co., and Sun Country Airlines Inc.
They will fly to nine Cuban cities, not including Havana. The DOT is still determining which carriers will be allowed to fly to the Cuban capital.

As I looked further, I see that they have not given routes to Havana yet. United and Delta will likely get approved for those later.