Asterixm, technically you are correct.  However, if I remember my history correctly,  all of our ancestors originated in Africa or in that general vicinity.  Given that they seemed to be the first inhabitants of North America, and that they have been here +/- 12,000 years would hardly qualify them as immigrants in the practical sense. Do we refer to British born people as immigrants?  They've been in Great Britain less than 12,000 years.