Southwest will launch its first five routes from Chicago O'Hare on Feb. 14.
The carrier will fly four times daily from O'Hare to Nashville, Baltimore and Dallas Love Field. Southwest will also fly six times daily from O'Hare to Denver and twice daily from the northern Chicagoland airport to Phoenix.
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The flights will augment Southwest's enormous operation at Chicago Midway, on the city's south side. Southwest first announced that it planned to serve O'Hare on Oct. 12.
The carrier has also set a launch date of March 11 for Colorado Springs, Colo., service. Southwest will serve Colorado Springs from Denver, Las Vegas, Phoenix, Dallas Love Field and Chicago Midway.