We wrote about Delta Air Lines’ triple bonus miles offer on Delta’s shuttle service between New York and Chicago last month, and it didn’t take long for American Airlines, United and JetBlue to match Delta’s offer. Through Aug. 31, 2010, American AAdvantage members can earn triple bonus miles and triple elite-status qualifying miles (EQMs) on American Airlines or American Eagle flights between New York La Guardia and Chicago O’Hare or Boston. Registration prior to travel at http://insideflyerus.wpengine.com/link/?2680 is required. The offer applies to new reservations booked between June 14 and Aug. 31, 2010. The triple mile bonus applies to miles only and not elite qualifying miles or segments.

JetBlue TrueBlue members will earn triple points on flights between New York and Boston or Chicago through Aug. 31, 2010. Members can also earn triple points on flights between Chicago and Boston and between Los Angeles and New York or Boston. Registration at http://insideflyerus.wpengine.com/link/?2689 is required. With this offer, members can earn 12 points per dollar spent when booking a flight online at jetblue.com.

United Mileage Plus members can earn triple miles when flying between New York and Chicago through Aug. 31, 2010, but the offer is only valid for members residing in Illinois, Indiana, Wisconsin, New York, Connecticut or New Jersey. Registration is required prior to travel at http://insideflyerus.wpengine.com/link/?2688 — Registered members will receive triple flight miles and triple EQMs on nonstop United and United Express flights on itineraries for travel solely between Chicago O’Hare and New York LaGuardia.