>>19198805 lb/pb
They're available up to the Clinton Administration:
https://history.state.gov/historicaldocuments
https://history.state.gov/historicaldocuments/about-frus
The Foreign Relations of the United States series presents the official documentary historical record of major U.S. foreign policy decisions and significant diplomatic activity. The series, which is produced by the Department of State's Office of the Historian, began in 1861 and now comprises more than 450 individual volumes. The volumes published over the last two decades increasingly contain declassified records from all the foreign affairs agencies.
Foreign Relations volumes contain documents from Presidential libraries, Departments of State and Defense, National Security Council, Central Intelligence Agency, Agency for International Development, and other foreign affairs agencies as well as the private papers of individuals involved in formulating U.S. foreign policy. In general, the editors choose documentation that illuminates policy formulation and major aspects and repercussions of its execution. Volumes published during the last three decades have expanded the scope of the series by including documents from a wider range of government agencies, particularly those involved with intelligence activity and covert actions.