The UFCW claims they represent at least 800,000 grocery workers across the US.

I had a job as a union worker in a supermarket, and am glad that's still available to others.

https://www.ufcw.org/actions/campaign/albertsons-and-safeway...

My brother has worked as a stocker for King Kullen in New York for 20 years and is a union worker.

In the Seattle area where the poster is from, pretty much all the grocery stores are unionized. Workers at big stores like Safeway, Fred Meyer, QFC, and Albertsons, and local stores PCC, Uwajimaya are represented by UFCW3000. https://ufcw3000.org/shop-union

Additionally, Teamsters 174 organizes a lot of the grocery freight workers. https://teamsters174.net/warehouse-and-grocery/

Jewel-Osco: https://www.local881ufcw.org/about-us/#local-881 Meijer and Kroger: https://ufcw951.org/about/

The more-expensive stores sometimes do. My friend's wife works for one, and the store is closing because it's too close to a discount grocery to get enough traffic to stay open. The union is making her transfer to a much further location or lose her seniority, for some nonsense reason involving the closer locations historically being part of a different union, despite them now all being the same one.

Most grocery stores in the US are still heavily union. I don't think the unions ever left the grocery stores.

Literally all the grocery stores in my Northeast US city are unionized.