Introduced by American Airlines in 2008 as oil prices spiked, fees for checked airline luggage were among the first levied by airlines. According to The Associated Press, U.S. airlines collected $3.4 billion in bag fees in 2010. Typically, the service fees are $50 per round trip for the first piece of checked luggage.
Most major U.S. airlines have similar service fees. JetBlue has no fee for the first bag, while Southwest allows two free checked bags per customer. The easiest way to avoid the fee is to carry your luggage on the plane, and store it in the overhead compartment or under your seat. And don't pack more than you need.