CHICAGO (CBS) -- Unionized workers at UPS are gearing up to walk off the job.
That could happen as soon as their contract ends at the end of the month.
The last UPS strike was in 1997 and lasted 16 days.
CBS 2 spoke to a professor of labor and employment relations who said a strike would impact other businesses because of the supply chain disruption.
He also said it could lead to other unions forming.
"I think something that's important in this strike is we have to keep an eye on Amazon. I think if the teamsters win a good contract at UPS, they'll then use it to go after Amazon and try to convince those workers to organize," said Robert Bruno of the University of Illinois.
The contract covers 340,000 workers.
If they walk out, it would be the largest single-employer strike in U.S. history.
for more features.