I ran across a Pennsylvania (GR&I) document yesterday titled DATA SHOWING RATES OF PAY OF COMMON AND UNSKILLED LABOR IN INDUSTRIAL PLANTS SERVED BY THE RAILROADS. It shows: Name of Firm; Industry; Class (of laborer); 1920 Pay Rate; 1921 Pay Rate; Percent Reduction (if any), Work Force Present. The document was labeled SUPPLEMENT "A", pages numbered 59-62, so perhaps these were just additions to the main body which would account for the small listing for Cadillac.
I am just showing the names & types of industries below.