American went all the way to the U.S. Supreme Court in a failed bid to block the election.
American argued that the union should have been required to show support from 50 percent of eligible workers before an election under a change in voting rules approved by Congress in February 2012. But the union argued that it only needed 35 percent support to force a vote under rules that were in effect when it filed for an election, and the courts upheld that view.
The agents are the largest bloc of nonunion workers at American. The airline's pilots, flight attendants and ground workers are represented by other unions.