The archives of the US Department of State are housed at the US National Archives in College Park, Maryland. Many relevant document have been released from the State Department's archives under US Freedom of Information law, including a mass of Falklands material.
1967: MT's first visit to the U.S.
MT first visited the US in 1967, aged 41, as a guest of the State Department's International Exchange Program. She travelled the country for a full six weeks, stopping briefly in most of the major cities. Denis Thatcher accompanied her, paying his own way.
She was enthused. The trip had a great impact on her, leaving her with an abiding sense of the energy, prosperity, openness and entrepreneurism of the US, as well as a sympathetic feeling for its politics and a sense of being among allies and friends.
The surviving records of the visit are typical of the sources from which modern political historians produce their books: the file consists of administrative fragments, frustratingly incomplete but allowing occasional glimpses of the subject, such as MT feeling a little lonely in Washington (an experience not repeated in later years).
A British historian has written an article about the visit:
1973: a lunch with Mrs.T
In May 1973 MT had a chatty lunch at the Connaught Hotel with an American official who reported her views on the contemporary political scene to his superiors. It is impossible to believe she knew the conversation was being noted in quite this style.
The document was forwarded to the Department of State by Walter Annenberg, then US Ambassador to London, later a friend and supporter of Ronald Reagan whom MT sometimes visited on her US trips many years later.
Annenberg's cover note assessing MT is almost as interesting as the conversation itself. He judged her"a strong supporter of Heath and ... a very real political asset to the Government". He was not, however, especially impressed with her (at this time anyway) describing her political performance as "solid, respectable and unspectacular" and voicing the common judgment of contemporaries (MT included, probably): "Once touted as a potential first woman Prime Minister, it is most doubtful that she could, or does, realistically expect to lead her party".
The memorandum records MT's rapid fire judgment of a number of colleagues as well as her views of general politics at the time.
The document was opened in 1998.
1982: State Department Falklands files
The State Department has released to the Margaret Thatcher Foundation a mass of diplomatic telegrams and other documents relating to the Falklands War. Selections will be uploaded.
1970-88: cia files
Understandably, and justifiably, the CIA has a reputation for secretiveness. In fact, though, it has released a good many documents relating to Margaret Thatcher, and particularly to the Falklands War. These are available to the public at present only via a little used database in National Archives II at College Park. Selections will be uploaded on this site.