This website gives all the descent of Bonaparte family. There is only one member of the House of Bonaparte to come to the United States, Jerome Bonaparte, came to Baltimore and married an American, Elizabeth Patterson. He was called back to France, had his marriage annulled and was forced to marry the Catherine of Wurtemburg.
The website for information on the House of Bonaparte and descendants to modern times is:
http://napoleon1er.perso.neuf.fr/E-Genealogie.htmlWhat is your ancestor's name?