When Delta merges operations with Northwest later this year, it's unlikely that the combined airline will operate six hubs, especially since some of them are relatively close to each other.

Which ones will go? Atlanta or Memphis? Detroit, Cincinnati or Minneapolis? Will they keep Salt Lake City? Whatever happens, Norwelta will cut some routes, and there will be room for other airlines to nose into these hubs, and Southwest, not surprisingly, is the first to make a move. Beginning in March, the Dallas-based low cost carrier will begin service between Chicago Midway and MSP, which will bring low cost connecting service to cities Southwest serves from Midway. Minneapolis desperately needs another low cost airline, especially if Sun Country, which is experiencing financial difficulties, doesn't survive.