Iron industry and trade 163 History 104 Iron and steel workers 35 Steel industry and trade 29 Iron mines and mining 19 Iron 17 Iron-works 15 more ... Iron foundries 14 Coal mines and mining 11 Iron industry and trade--Pennsylvania 10 Ironwork 9 Labor unions 9 Cast-iron 8 Economic conditions 8 Railroads 8 Wrought-iron 8 Tariff 7 Biography 6 Building 6 Building, Iron and steel 6 Iron ores 6 Blast furnaces 5 Labor and laboring classes 5 Social conditions 5 Anthracite coal 4 Businessmen 4 Equipment and supplies 4 Fer 4 Histoire 4 Historic sites 4 Industries 4 Iron Manufacturing--19th century 4 Iron founding 4 Iron industry 4 Metallurgy 4 Mines and mineral resources 4 Steel industry 4 Steel, Structural 4 Steel-works 4 Streets 4 less ...