Commerce 14 Railroads 3 Description and travel 2 Economic conditions 2 Articles of incorporation 1 Canals 1 Commerce--19th Century 1 more ... Commerce--Philadelphia--19th century 1 Freight 1 History 1 Industry 1 Interstate commerce 1 Pennsylvania--Economic conditions--19th century 1 Philadelphia (Pa.)--Commerce--History--19th century 1 Rates 1 Shipping--Pennsylvania--Philadelphia 1 Trade Regulations--19th century 1 Trade and professional associations--Philadelphia (Pa.)--19th century 1 Trade and professional associations--Philadelphia (Pa.)--20th century 1 Trade--Pennsylvania--19th century 1 Transportation 1 less ...