American History, 1493- 1945 The Gilder Lehrman Institute of American History’s archive of letters, diaries, maps pamphlets, printed books, newspapers and ephemera sheds light on the political, economic and social history of the United States up until the 20th Century. The majority of the collection is unique manuscript. It is an extensive resource for scholars, educators and students and is considered one of the finest archives for material on the revolutionary, early national, antebellum and civil war eras.