UPS union likely to authorize strike

CHICAGO (CBS)-- On Friday, members of the Teamsters Union are expected to authorize a strike that could bring UPS operations to a screeching halt.

A "yes" vote doesn't mean the strike will happen, but it would allow 340,000 UPS employees to walk off the job in August 1.

The union has been negotiating with the company for months, asking for higher pay, more full-time jobs and no excessive overtime.  

It would be the largest single-employer strike in the U.S. since the 1950's. The impact on the economy could be devastating.

UPS delivers 17 million packages in the United States per day.