Source: Dan Reed, USA Today

Southwest (LUV) and AirTran (AAI) on Tuesday launched sales featuring fares as low as $25 one way for winter, when planes otherwise could be half-empty.

Southwest is offering the lowest fares on some of its routes in 13 years. The one-way sale prices — good for travel Dec. 2-16 and again Jan. 5-Feb. 20 — are $25 on routes up to 375 miles, $50 on routes up to 549 miles, $75 on routes up to 999 miles and $100 on longer routes. The sale expires at midnight PT Thursday.

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