Hart, Albert Bushnell (1854-1943), an American historian, encouraged the study of history by investigating original sources. He wrote or edited about 100 volumes of history and government. His books include The Formation of the Union (1892), Slavery and Abolition, 1831-1841 (1906), National Ideals Historically Traced (1907), The War in Europe (1914), and America at War (1917). Hart was born in Clarksville, Pennsylvania. He taught at Harvard University from 1883 to 1926.