WASHINGTON — The Obama administration on Friday authorized six American airlines to begin direct flights to Cuba as soon as fall, paving the way for the resumption of scheduled air travel between the United States and Cuba after more than 50 years.

The Department of Transportation said it had approved applications from American Airlines, Frontier Airlines, JetBlue Airways, Silver Airways, Southwest Airlines and Sun Country Airlines to begin flying to Cuba from Miami, Fort Lauderdale, Chicago, Philadelphia and Minneapolis-St. Paul.

The action was the latest piece of President Obama’s push to normalize relations between Cuba and the United States after more than half a century of hostility. In place of American efforts to isolate Cuba, an island nation 90 miles south of Florida, the new policy encourages Americans to travel there.

The service approved on Friday will fly to nine Cuban cities, including Cayo Largo, Cienfuegos, Matanzas and Santiago de Cuba. The Transportation Department said it would announce routes to Havana, the capital, this summer. Those could include service from New York, Washington and Boston, for which several major carriers have applied.