Genealogy 14 World War, 1939-1945 9 Pennsylvania--History--Colonial period, ca. 1600-1775 7 Pennsylvania--History 6 United States--History--Revolution, 1775-1783 6 Medicine 4 Philadelphia (Pa.)--History--20th century 4 more ... Philadelphia (Pa.)--Politics and government--20th century 4 Quakers--Pennsylvania--18th century 4 Slavery 4 World War, 1914-1918 4 AIDS (Disease) 3 African Americans 3 African Americans--Pennsylvania--Philadelphia 3 Artists--United States 3 Books and Bookselling--19th Century 3 Family life--Pennsylvania--19th century 3 Family life--Pennsylvania--20th century 3 Family life--Upper Class--19th century 3 Floods--Pennsylvania--Johnstown (Cambria County) 3 Genealogists 3 Genealogists--Research 3 International trade--19th century 3 Local transit--Pennsylvania--Philadelphia 3 Love-letters 3 Municipal officials and employees--Pennsylvania--Philadelphia 3 Museums--Pennsylvania--Philadelphia--20th century 3 Native Americans 3 Philadelphia (Pa.)--City government--20th century 3 Philadelphia (Pa.)--City planning 3 Philadelphia (Pa.)--Officials and employees 3 Slavery--United States--History 3 Spouses--Correspondence--19th century 3 Spouses--Correspondence-–20th century 3 Theater--Pennsylvania--Philadelphia 3 United States--History--Colonial period, ca. 1600-1775 3 United States. Army--Recruiting, enlistment, etc 3 Women--Authors--20th century 3 World War I. 3 World War II 3 less ...