Southwest Airlines plans to begin non-stop flights to Las Vegas and Phoenix from Atlanta from 10 March 2012.
The carrier, which has an all Boeing 737 fleet, will operate on both routes daily.
Southwest announced last month it would start flights to the Atlanta market from 12 February, with services to five cities: Baltimore, Chicago Midway, Denver, Houston Hobby and Austin.
"An expansion like this quickly solidifies our commitment to the Atlanta market before we've actually started service there," said Bob Jordan, Southwest Airlines executive VP of strategy and planning and AirTran Airways president.
AirTran, which was acquired by Southwest, already operates between Atlanta and Las Vegas and between Atlanta and Phoenix, schedules in Innovata show. Southwest will also compete against Delta Air Lines on both routes, and against US Airways on Atlanta-Phoenix.