Delta started it all off by offering 2,500 bonus SkyMiles on Delta Shuttle flights between New York La Gaurdia and Boston or Washington Reagan. Seeing as Northwest is married to Delta, they are also offering 2,500 bonus WorldPerks miles on those same Delta Shuttle flights. Next came American Airlines, by offering the same amount of AAdvantage miles but only on the New York to Boston route. Finally US Airways is ponying up 2,500 bonus miles on US Airways Shuttle flights between the three cities. The only difference with US’s offer is that their’s runs until Aug 15 whereas all the others only run until Jul 26.