After a contentious summer, the grocery industry may be in for more strikes as workers increasingly demand improved working conditions.

In a series of strike votes over the summer, members of United Food & Commercial Workers (UFCW) in Oregon, Washington and California have voted overwhelmingly to authorize strikes if contract bargaining fails to produce acceptable union contracts.

According to Salon.com, United Food and Commercial Workers (UFCW) Local 555 voted on Aug. 24 to authorize a strike for 20,000 grocery employees at Safeway, Albertsons, QFC and Fred Meyer locations in the Pacific Northwest.

Last week, the Oregon AFL-CIO debuted a proposed ballot initiative that would limit any grocery store to two self-checkout machines.

The labor unrest in Oregon comes two months after union members voted to authorize a strike for about 46,000 grocery employees in Southern California. The workers reached a tentative deal, averting a strike, and grocery associates in the region subsequently voted overwhelmingly to ratify the contract. Northern California has also experienced labor disputes, although agreements have also been reached between workers and Safeway and its Vons chain, and the Save Mart, FoodMaxx and Maxx Value banners.

Grocery workers in the West say that they want higher wages and an end to the gender pay gap.

Meanwhile on the East Coast, UFCW members have been picketing outside Lidl stores all summer, trying to persuade workers to unionize.

Earlier this summer, union members declared victory in New England following a successful 11-day strike by Stop & Shop workers.