In late August 1974, thousands of Teamsters Local 804 members in New York went on strike against their employer, United Parcel Service (UPS), for the third time in six years. A decade earlier, UPS had begun laying off full-time package sorters in its distribution warehouses and hiring part-time workers, who were paid roughly the same wage but lacked fringe benefits like pensions or vacation days, as their replacements. UPS wanted to expand the practice, but workers saw the demand for what it was: an existential threat to their good-paying, full-time union jobs.

Led by their charismatic, thirty-eight-year-old local president Ron Carey, Local 804 members hit the picket line after contract negotiations broke down. By the end of the bitter walkout, a Teamster from a nearby New Jersey local had plowed their truck through 804’s picket line, killing one of Carey’s closest friends, and the federal government was called in to mediate a settlement. But in the final agreement, Local 804 successfully slowed, though they could not completely stop, the proliferation of part-time work in UPS facilities. That would soon change — for the worse.

In 1982, the national Teamsters union agreed to a “two-tier” system that divided the pay of part-time and full-time UPS workers. The company permanently cut part-timers’ starting pay nationwide by 25 percent, down to $8 an hour, which would be raised only fifty cents over the next thirty years. The company steamrolled ahead in its expansion of part-time work, building a package empire on the back of a workforce that, by the mid-1990s, was 60 percent part-time workers.