Southwest will launch Minneapolis/St. Paul service on March 8 with eight daily roundtrips between MSP and Chicago Midway.
The airline revealed its intention to begin service from the Northwest Airlines-dominated airport on Oct. 1.
Fares purchased at least 21 days in advance start at $69 each way, said Southwest.
For its spring schedule, Southwest will also launch service between Phoenix and Birmingham, Ala. It will discontinue flights between Kansas City and Tulsa, Okla.; Tampa and Albuquerque, N.M.; Lubbock and El Paso, Texas; and Albuquerque and Amarillo, Texas.