UPS loaders describe working conditions and union-management collusion - World Socialist Web Site Earlier this week, United Parcel Service workers voted by 93 percent to authorize the Teamsters union to call a strike when the five-year labor agreement covering more 230,000 drivers, warehouse and other workers at UPS hubs and air cargo operations across the US expires on July 31. UPS Freight workers, including over-the-road and city truck drivers and associated workers, voted by 91 percent to strike. The overwhelming strike vote is part of the growing militancy of workers in the US and internationally. Since the beginning of the year, hundreds of thousands of teachers and other workers in the US have joined strikes and mass protests that have placed workers in increasingly direct conflict with the corporatist unions. With nearly a quarter-of-a-million unionized workers, UPS is the largest unionized private sector employer in the US. The Atlanta-based company is also synonymous with speed up, workplace injuries and low-paid part-time labor, with workers often saying UPS stands for Under Paid Slaves. In the mid-1970s, UPS blazed the trail for corporations throughout America and the world with the introduction of a part-time casual workforce.