According to Forbes, there are 374 Billionaires in the US (26 of their Forbes 400 richest Americans are NOT billionaires).  http://www.forbes.com/free_forbes/2005/1010/089.html\n\nAccording to http://answers.google.com/answers/threadview?id=6330 , there were 17.1 Million Millionaires in the US in 2002.\n\nAccording to one source, 1 in 125 Americans are millionaires (as of 2004).  http://www.globalpolicy.org/socecon/inequal/2004/0615millionaires.htm\n\nPartial answer, partial credit?  Hope it helps.
How many millionaries and billionaries?