Check out this excellent guide to finding archives from Sam Houston State.
Search LibrarySearch for primary sources
Search EmoryFindingAids for Emory archival collections
Don't know where to start? Try one of the following database portals. They allow researchers to search across the web and multiple databases produced by the same publisher.
Access a diverse range of primary source materials from the 18th and 19th century America. Includes the Colonial Period, major wars, African-American History, the Industrial Revolution and more.