The U.S. Constitution prohibits the giving of a title of nobility by the American Government (Congress, the President, or the Judicial) or the receipt of the same "from any King, Prince, or foreign State" by high public officials during their terms of office, or by military personnel while enlisted.
Private American citizens are free to accept and use titles of any kind whatever, noble or otherwise.
Citizens of the United States like to think that we are classless and untitled, cherishing these egalitarian concepts as marks of the unique American opportunity for upward mobility in class and power. In everyday practice, however, Americans are very much aware of how to create and use
titles to establish class and wield power. A primary example of the importance of a title as a mark of power and status is the title "Ms." (rhymes with fizz), created some years ago by feminists for use in the place of "Miss" or "Mrs," both of which titles show a woman's relationship to a man. The title "Ms." is egalitarian in that it shows gender only, exactly as does the modern "Mr." (L.G. Pine, in The Story of Titles, discusses the original and modern uses of "Mister," a variation of "Master." Interestingly, like "Ms.," most royal and noble titles are themselves egalitarian in that they show gender only--for example, a Queen is not necessarily the wife of a King, a Baroness is not
necessarily the wife of a Baron.) The general acceptance and use of the once artificial "Ms." show that Americans clearly understand and acknowledge the value and importance of the title as an empowering device.
A legitimate noble title always has a legitimate royal source, called a fons honorum (Latin: "source of honor," the "fountainhead" from which the legitimate title is issued). What is important to know is that noble titles do not come from governments, but from heads of royal families, called
a "royal house." Thus, the royal house is a dynastic family holding hereditary royal title and prerogatives usually based upon modern or ancient geographical rulership; the royal dynastic family need not necessarily currently head a government or rule a nation. A government is not, of itself, royal, nor can a government declare itself royal--it is persons who are royal or
noble, and it is the head of that government who is royal. Thus, a government as an entity is not and cannot be a fons for royal or noble titles (Which makes the American Constitution's prohibition perfectly proper.). In fact, the universal practice is that a government which prefers a royal head of state doesn't create it, but goes, instead, to one of the royal houses (in Europe or elsewhere) to find a monarch to reign. Observe the actions of the British Parliament when, in 1701, it became apparent that King William and Queen Anne were not going to leave any heirs in line for the throne. Parliament wanted, of course, a Protestant sovereign, but even the British Parliament had
not the authority to create royalty, nor could the King and Queen declare an heir. Therefore, Parliament, understanding that governments do not beget royalty, began to carefully scrutinize Europe's royals, searching for a suitable candidate to come to the throne after King William's death. Having analyzed genealogies and religious proclivities, Parliament settled on the Electress of Hanover, who had the virtue of being the granddaughter of James I. However, the Electress died before the British throne became available, so the office passed to her son, George Ludwig who became King George I of England.
HMQEII bestowed knighthoods on both Ronald Reagan and George H.W. Bush --- AFTER they had left office.
If you have a title and an American doesn't use it when addressing you...well, they don't have to. Here you are just Ms., Mr., Mrs. or Miss.