How do I tell the difference between primary and secondary sources?
Primary sources are actual historical documents written during the period you are investigating. Secondary sources are books and articles written by historians at a later date. For example, a primary source from 1862 might be an article or an advertisement in the New York Tribune, while a book about the New York Tribune in 1962 would qualify as a secondary source. Similarly, a farm ledger, painting, or circus flier from 1890 is a primary source while a secondary source on the same subject could be a book about selling cotton, American artists, or nineteenth-century entertainment.
