Foreign Relations of the United States (FRUS) is the official historical record of U.S. foreign policy decisions that have been declassified and made available in this set. FRUS is produced by the U.S. State Department's Office of this Historian. Types of documents in FRUS include correspondence, text of treaties, Presidential and other messages. FRUS is great trove of primary source material for various topics.
There are several different tools that provide online access to FRUS. There are gaps in various tools be sure to check the dates of coverage with each search.
The Blume Library and Law Library have some copies in print. See the library catalog link below for details.
Other FRUS Sources