Thousands of low-wage workers marched in New York, Los Angeles and other U.S. cities on Thursday calling for minimum pay of $15 an hour in a cause that has scored major legislative victories in California and New York state in recent weeks. The union-backed "Fight for $15" campaign has expanded since its inception in 2012 from a movement mostly centered on the fast-food industry to encompass other low-wage sectors, such as home health care, retail outlets and hospitals.