Southwest Airlines received approval from the Department of Transportation to operate new service between Washington's Reagan National airport and Houston's Hobby airport.
The slot exemptions became available when Spirit Airlines stopped using its slots for flights between Reagan National and Fort Lauderdale.
"Southwest's service will provide air travelers with a new, low-cost option when they fly between Reagan National and Houston," said Transportation Secretary Ray LaHood in a statement.
Southwest beat out US Airways and JetBlue Airways who had also applied for permission to use the slots. US Airways had proposed service to Oklahoma City while JetBlue wanted to start service to Jacksonville, Fla.
Southwest will have to begin its new service to Houston by August 5, according to the DOT ruling.