Royal descent is now recognized as not infrequent among residents of the United States, as in other countries. At one time, publications on this matter stressed royal connections for only a few families. One example included James Pierpont and others. Too, we see NEHGS articles on "tycoon" families and US presidents of royal descent that emphasize the discriminating notion. That is, those of royal descent excel (to wit, Roberts' article on eminent descendants of Mrs. Alice Freeman Thompson Parke). Many, too, were at the forefront of social progress, for example, Anne (Marbury) Hutchinson who was banished from the Massachusetts Bay Colony for her progressive beliefs.
However, with improved documenting methodologies, it can be estimated that as many as 150 million Americans have traceable royal European descent. According to American genealogist Gary Boyd Roberts, an expert on royal descent, most Americans with significant New England Yankee, Mid-Atlantic Quaker, or Southern planter ancestry are descended from medieval kings, especially those of England, Scotland, and France. William Addams Reitwiesner documented many U.S. descendants of Renaissance and modern monarchs. Some Americans may have royal descents through German immigrants who had an illegitimate descent from German royalty.
Due to primogeniture, many colonists of high social status were younger children of English aristocratic families who came to America looking for land because, given their birth order, they could not inherit. Many of these immigrants initially enjoyed high standing where they settled. They could often claim royal descent through a female line or illegitimate descent. Some Americans descend from these 17th-century British colonists who had royal descent. There were at least 650 colonists with traceable royal ancestry, and 387 left descendants in America (almost always numbering many thousands, and some as many as one million). These colonists with royal descent settled in every state, but a large majority lived in Massachusetts or Virginia. Several families which settled in those states, over the two hundred years or more since the colonial land grants, intertwined their branches to the point that almost everyone was somehow related to everyone else. One writer observed, "like a tangle of fish hooks".
Over time, opposing factors have affected the percentage of Americans who have provable royal descent. The passage of the generations has further intermingled the ancestry of the English colonists' descendants, thus increasing the percentage who descend from one of the immigrants with royal ancestry. At the same time, however, waves of post-colonial immigrants from other countries decreased the percentage who have royal descent.
http://en.wikipedia.org/wiki/Royal_desc ... ted_States