Columbia subject headings:
Industries--United States--History--19th century.
Manufacturing industries--United States--History--19th century.
Technology--United States--History--19th century.
United States--Economic conditions--1865-1918.
Harvard subject headings:
Industries--United States--History
United States--Economic conditions--1865-1918.
United States--Economic conditions.
Working class--United States--History
Princeton subject headings: