NEW YORK —  Fast-food workers staged strikes at McDonald’s and Burger Kings and demonstrated at other stores in sixty U.S. cities on Thursday, Aug. 29, in their latest action in a nearly year-long campaign to raise wages in the service sector.

The strikes spread quickly across the country and have shut down restaurants in New York, Chicago, Detroit, Milwaukee, St. Louis, Raleigh and Seattle, according to organizers.

The fast-food workers were expected to be joined by retail staff from stores owned by Macy’s Inc, Sears Holdings Corp and Dollar Tree Inc.

The fast-food workers want to form unions in the virtually union-free sector without employer retaliation and bargain for higher wages.

They are demanding pay of $15 an hour, up from $7.25, which is the current federal minimum wage.

Martin Rafanan, a community organizer in St. Louis, said local employees of McDonald’s and Wendy’s can’t make a living on the salaries.

McDonald’s profits totaled $5.47 billion in 2012.

Restaurant chains and trade groups say the protests are unwarranted because fast-food and retail outlets provide Americans with millions of good jobs with competitive pay and ample opportunities to rise through the ranks.

“Our history is full of examples of individuals who worked their first job with McDonald’s and went on to successful careers both within and outside of McDonald’s,” McDonald’s said in a statement.