I believe this photo is part of The Pittsburgh Survey from 1907, "Homestead: The Households of a Milltown" by Margaret Byington. The laborers worked 12-hour days for two weeks, then on Sunday at the end of the two weeks worked 24 hours to switch them to the next shift, which they did for the next two weeks, and over and over. No unions then. Well, there was a union, but it was crushed in 1892 and wouldn't form again until the late 1930s.