Flight-by-flight and route-by-route, scheduled airline connections between the United States and Cuba are falling. Southwest Airlines is the latest carrier to cut routes, pulling out of the resort cities of Varadero and Santa Clara. The cities come off Southwest’s route map after the U.S. Labor Day holiday. Southwest cites “the continuing prohibition in U.S. law (restraints that just became more stringent) on tourism to Cuba for American citizens.” While the first round of reductions is at least, in part, because of more robust restrictions in relations between the two countries, earlier route cuts are the result of too little demand. Ultra-low-cost Spirit has ditched Fort Lauderdale-Hollywood-Havana service. American Airlines scrubbed one of its two daily Miami-Holguín departures, and similarly cut in half Miami-Santa Clara as well as Miami-Varadero service. It will offer just one round trip daily on those runs. Low-cost, high-frills JetBlue has already moved to smaller aircraft on routes from Miami to Havana, Santa Clara, Holguín and Camagüey. Ultra-low-cost Frontier just dropped Miami-Havana and Silver Airways pulled of all its Cuban routes. Southwest isn’t pulling out of the island completely, however. It’s softening the blow by asking the U.S. Department of Transportation for permission to field a third daily Fort Lauderdale-Hollywood-Havana departure.