Teamsters unionize Mill Rock workers, a sign for Costco warehouses

Teamsters Local 117 said June 26 that workers at Mill Rock Packaging voted unanimously to join the union, bringing new material handlers into an existing bargaining unit already covered by the local. The workers were seeking workplace protections, higher wages, affordable health insurance, and better retirement benefits, and material handler Curtiss Jackson said the change should help bring fairer treatment on the job.

The win lands in a part of the labor market Costco employees know well: fast-moving, physically demanding work where staffing, safety, training, pace, and discipline can all turn into grievance issues if management does not respond early. Teamsters Local 117 says it represents 19,000 workers across Washington State, and the union’s Warehouse Division covers warehousing, distribution, lift truck operators, equipment operators, drivers, and clerical employees, the same broad operational world that surrounds Costco’s warehouses and distribution centers.

For Costco workers, the bigger signal is that the Teamsters have kept adding pressure to the company from multiple angles. The union ratified its first-ever national master agreement for Costco workers on October 21, 2022, a contract covering more than 18,000 workers nationwide. In December 2023, about 200 Costco workers in Norfolk, Virginia, won union representation, the first Costco group to do so in more than two decades. In April 2024, more than 150 Costco drivers in Sumner, Washington, voted to join Teamsters Local 174, becoming the first Costco distribution center workers to unionize.

The bargaining fight did not stop there. Teamsters said negotiations for a new Costco national agreement were suspended in August 2024 after Costco refused a card-check agreement that would have made it easier for nonunion workers to organize. In January 2025, Costco Teamsters voted 85% to authorize a strike ahead of the contract deadline, then later reached a tentative agreement that avoided a walkout. The union said that 2025 agreement delivered large wage gains, a 22% boost in pension contributions, and more than 40 language improvements, including stronger seniority, vacation, shop steward, and anti-surveillance protections.

That track record matters because Costco’s own Teamsters page says nonunion workers get handbook benefits rather than contract protections. For employees on the floor, in receiving, at the docks, or on forklifts, the Mill Rock vote is another sign that Teamsters organizing is still finding traction in supply-chain jobs where the daily work is intense and the bargaining table can shape pay, scheduling, and job security long before a dispute reaches a strike threat.