Centennial Exhibition (1876 : Philadelphia, Pa.) 5 Coal mines and mining--Pennsylvania 5 Railroad History--Pennsylvania 5 Railroads--Pennsylvania--19th century 5 Accounts--19th century 4 Local transit--Pennsylvania--Philadelphia 4 Pennsylvania Railroad--19th century 4 more ... Railroad Equipment--19th Century 4 Railroads 4 United States--History--Civil War, 1861-1865--Personal narratives 4 Canals and railroads--19th century 3 Estate administration--19th century 3 Floods--Pennsylvania--Johnstown (Cambria County) 3 Genealogy 3 Philadelphia Views--19th century 3 Railroad Equipment--20th Century 3 Railroad stations--Plans 3 Slavery--United States--History 3 Social life and customs--19th century 3 Social life and customs--Pennsylvania--Philadelphia (Pa.)--19th century 3 Spouses--Correspondence--19th century 3 Street railroads--Pennsylvania 3 Underground Railroad 3 World War, 1939-1945 3 Architecture--20th Century 2 Art and Artists--Pennsylvania--Philadelphia--19th Century 2 Artists 2 Artists--United States 2 Banks and banking--Pennsylvania 2 Business mergers and acquisitions--20th century 2 California--Description and travel--19th Century 2 Cemeteries–-Pennsylvania 2 Charities--Pennsylvania--Philadelphia 2 Coal Industry--20th century 2 Commemorative Celebrations--Philadelphia 2 Engineering--Pennsylvania--Philadelphia 2 Engineering--Problems, exercises, etc 2 Ephemera 2 Family life--Pennsylvania--20th century 2 Family life--Personal correspondence--19th century 2 less ...