The modern economy revolves around the sprawling logistics industry. Nothing demonstrates this more clearly than the current situation at Amazon and UPS. If Amazon makes good on its recent pledge, it will add another 100,000 workers to its US workforce by 2018, making it one of the country’s largest — and one of the largest nonunion — employers.

The US labor movement faces several existential threats right now, but Amazon’s is a special kind. The company’s breakneck expansion has revolutionized the logistics industry. Its impact is most deeply felt at United Parcel Service (UPS), the country’s largest private-sector, unionized employer, with nearly 250,000 of its workers represented by the Teamsters.

UPS already lashes the Teamsters with the threat of Amazon undercutting the union’s gains to justify the miserable wages paid to part-timers, impossible productivity demands, and the subcontracting of union work to non-union contractors. It will no doubt use the competition from Amazon to demand further concessions from the Teamsters during the next round of contract negotiations.