American Airlines, Delta Air Lines and United Airlines have joined the stampede to raise checked bag fees, adding 20 percent to the cost of the first checked bag. American announced on Thursday that it would join other airlines in increasing baggage fees, raising the price of the first checked bag by $US5 to $US30 for tickets purchased from September 21. A second checked bag also goes up by $US5 to $US40 for travel in the US as well as other North American and Caribbean destinations. The airline said it was following moves by other airlines to raise their fees. READ: Luggage fees soar as airline bagmen strike American noted this was the first rise in checked bag fees since 2010 and that some customers would still be eligible for free bags. These included flyers with elite status, others with certain credit cards and customers traveling on military fares. Customers confirmed in first,  business class or premium economy would also not be slugged. American’s move followed increases at Delta, United, JetBlue, WestJet and Air Canada. Airlines say the rises are to help offset higher costs, including raised fuel prices and increased labor costs. But they are also a sizeable contributor to carriers'  high profits. US Department of Transportation statistics show US carriers between them earned almost $US4.6 billion in checked baggage fees in 2017. American topped the list at just under $US1.2 billion. The luggage charges are part of a move to “unbundle” fares by charging a widening range of charges, fees and commissions. These are known in the game ancillary revenues and are often foisted on customers under the banner of “choice”. The IdeaWorks Company estimated ancillary revenues for the world’s airlines grew more than 20 percent in 2017 to reach $US82.2 billion. This included $US57 billion from “a la carte” passenger charges beyond the cost of a ticket such as extra legroom, food, drink and luggage.