WASHINGTON — Five big U.S. airlines might add flights to Havana after some carriers dropped service to Cuba’s capital.

The Transportation Department proposed Friday that routes go to American, Delta, United, Southwest and JetBlue. There could be 20 daily flights between the U.S. and Havana.

The routes opened after Alaska Airlines, Spirit, Frontier and Delta dropped service because of weak demand. Traffic could suffer from the Trump administration’s move to limit tourism. Americans must have one of 12 reasons to visit Cuba, including visiting relatives.

American and Delta would each add one daily flight from Miami; Southwest would add one flight daily from Fort Lauderdale, Florida; United would fly six times a week from Houston; and JetBlue would fly six times a week more from Fort Lauderdale, once a week from Boston.