Southwest Airlines has launched a new promotion in honor of their 40th anniversary. The promotion runs for only 72 hours on the Southwest website, and all airfares much be booked by June 23, 2011. Sale fares of $40, $80, and $120 each way are valid on trips August 23 – November 16, 2011.

– $40 airfares are good for flights 0-450 miles
– $80 fares are 451-1,250 miles
– $120 fares valid for flights 1,251 miles or greater