Columbia subject headings:
Harvard subject headings:
Labor policy--United States--History
Labor unions--Political activity--United States--History
Labor unions--Political activity--United States--History.
Labor unions--United States--History
Labor--United States--History
Working class--United States--History
Princeton subject headings:
Labor movement--United States--History.
Labor policy--United States--History.
Labor unions--Political activity--United States--History.
Labor unions--United States--History.
Working class--United States--History.