From another thread, it is RidersUSA defined as a patriotic biker group (not gang). So, I guess a MC.
My bet is that there will be independents (no club affiliation) and people wearing the colors of a number of different clubs, not just one single club.
We had a group in my area to raise money for charity, and had participation from a dozen or so clubs from the US and Canada, as well as a significant number of independents.