Flights between the United States and Cuba are expected to begin this fall or winter now that the U.S. Department of Transportation has given six airlines permission to offer commercial air service from five U.S. cities.

American, Frontier, JetBlue, Silver Airways, Southwest and Sun Country were approved this month to provide a collective total of 155 roundtrip flights per week from Miami, Chicago, Philadelphia, Minneapolis and Fort Lauderdale, Florida. The flights will reach Camaguey, Cayo Coco, Cayo Largo, Cienfuegos, Holguin, Manzanillo, Matanzas, Santa Clara and Santiago de Cuba.

The Cuban government needs to approve the flights, but some airlines are planning to start selling tickets, expecting that approval soon will be granted. The United States still prohibits tourist travel to Cuba, but trips are allowed for professional meetings, official business, journalist visits, educational and religious activities and several other purposes.

The U.S. Transportation Security Administration is completing a security review of the Cuban airports involved.

Service to Havana has not yet been granted by the U.S. Department of Transportation because airlines have requested many routes than are available under the U.S. agreement with Cuba. The department is expected to approve Havana flights this summer.

Only charter flights are currently operating between the countries, but an agreement reached between the United States and Cuba in February allows for up to 110 additional daily flights. An hourlong charter flight costs about $500, but commercial airlines are likely to charge much less.

Cuban flights increased by more than 18 percent in 2015 over the previous year. Currently, 46 airlines—including Air France, Aeromexico and Air Canada—fly to Cuba.