If you're planning to fly abroad this summer, pack light or prepare to pay up.
United Air Lines has joined Delta Air Lines in charging $100 for a second checked bag on certain international flights.
The higher checked bag charge took effect June 1 and applies to flights from the U.S. to Europe, Africa, India, the Middle East and come countries in South America. The list of frees can be found on the United Air Lines baggage fee page.
United had previously charged $70 for a second checked bag. Delta increased its second bag fee to $100 in January, up from its previous charge of $75.
In the past four years, baggage fees have become a significant source of revenue for airlines. In 2011, United collected about $277 million in bag fees, compared with $313 million in the previous year, according to federal statistics.