Here's a quote regarding hate groups. The entire article is very interesting to read, and the 900-something number of hate groups is cited there, but NOT THE NUMBER OF INDIVIDUAL MEMBERS:
Homegrown hate groups increase in number - Race & ethnicity- msnbc.com
"Their critics say that groups like NSM are the faces of homegrown hate, something the NSM denies. They instead call themselves a “white civil rights organization.” Its ultimate goal is to whitewash America. If they had their way, U.S. citizenship would be limited to “those of pure white blood”; minorities would live in the country as guests. All Jewish people and gays would be forced to leave and immigration would be prohibited.