Southwest Airlines just launched their 39th anniversary sale, with short flights starting at $39 each way. At Fly.com, we have found that most major airlines have matched the fares, meaning that now is a very good time to shop for fall flights. (The sale is valid for travel Sept. 8 to Nov. 17.) Fares have been steadily climbing this year, so $39 each-way fares are very rare indeed. Most of these routes were $59 each way or higher before the sale broke. For more information about the sale and sample fares, click here. This sale ends on Thursday, so act fast for the best selection.