The Public Papers of the Presidents is a series starting with Herbert Hoover and continuing through Barak Obama that contains messages to Congress, speeches, transcripts of news conferences, selected important press releases of the White House and other activities of the Presidents (read more information about the series). The print series is in the Government Documents Collection on the ground floor of the JB Duke Library. The online version of The Public Papers of the Presidents is available for Presidents Reagan through Obama.
For earlier Presidents see:
Papers of John Adams (print)
The Papers of Andrew Jackson (print)
The Correspondence of James Polk (print)
The Papers of Andrew Johnson (print)
The Papers of Ulysses S. Grant (print)
The Works of Theodore Roosevelt (print)
The Papers of Woodrow Wilson (print)
The Digital National Security Archive contains first hand accounts of historical events as well as declassified documents that reveal the operations of many international issues from post World War II through the 21st century. Letters, telegrams, situation reports, telephone coversations, cables and memoranda derived from the CIA, FBI, the State Department and Congressional material are included. Many were obtained by FOIA requests. These primary douments give insight into the American response to historical events.
Archives Unbound contains 99 sets of documents, each set focusing on a different topic, from the Middle Ages to the 20th Century. Documents include memos, letters, covert reports, records of agencies, churches, and goverments. Some are in languages other than English.
Both of these resources work best when searching within a collection, not across the whole database. It helps to know specific people, dates and incidents before searching.