Railroad History--Pennsylvania 5 Railroads--Pennsylvania--19th century 5 Pennsylvania Railroad--19th century 4 Railroad Equipment--19th Century 4 Railroads 4 Canals and railroads--19th century 3 Railroad Equipment--20th Century 3 more ... Railroad stations--Plans 3 Street railroads--Pennsylvania 3 Underground Railroad 3 Centennial Exhibition (1876 : Philadelphia, Pa.) 2 Floods--Pennsylvania--Johnstown (Cambria County) 2 Forest nurseries 2 Genealogy 2 Ironwork 2 Labor--Images--20th century 2 Land surveys 2 Local transit--Pennsylvania--Philadelphia 2 Pennsylvania--Surveys 2 Photography--Railroads--19th century 2 Railroad engineering 2 Railroad--Construction 2 Railroads--Business and operation--19th century 2 Railroads--Design and construction 2 Railroads--Design and construction--19th century 2 Railroads--Employees--19th century 2 Railroads--Management 2 Railroads--Pennsylvania 2 Social life and customs--19th century 2 Stenographers 2 Surveying 2 Transportation 2 Transportation--Railroad--Descriptions--19th century 2 United States--History--Civil War, 1861-1865--Transportation 2 Accounts--19th century 1 Advertising--20th century 1 African American abolitionists 1 African American families 1 African Americans--History--Fugitive slaves--19th century 1 African Americans--Pennsylvania--Philadelphia 1 less ...