If that happens, 280,000 Teamsters would walk off the job. It would be the largest U.S. strike since UPS workers last went on strike in 1997, for 16 days. UPS is the largest private-sector union employer in the United States.
The two sides have been negotiating since late March, but Teamsters are balking at a UPS proposal to create a new class of driver that would work weekends at no pay premium.
Current full-time drivers now earn an average of $36 an hour. Last year, UPS had $5 billion profit, and paid its CEO $14.6 million in total compensation.