Barely a week before the contract for more than 325,000 United Parcel Service workers expires, union and company negotiators have yet to reach an agreement to avert a strike that could knock the American economy off stride.UPS and the union, the International Brotherhood of Teamsters, have resolved a variety of thorny issues, including heat safety and forced overtime. But they remain stalemated on pay for part-time workers, who account for more than half the union’s workers at UPS.A strike, which could come as soon as Aug. 1, could have significant consequences for the company, the e-commerce industry and the supply chain.UPS handles about one-quarter of the tens of millions of packages that are shipped daily in the United States, according to the …
