This is the only species of Antennaria listed in both: the 2010 ''Vascular Plants of the High Sierra San Pedro Mártir, Baja California, Mexico: an Annotated Checklist'' by Thorne, Moran & Minnich; and the 2016 ''Annotated Checklist of the Vascular Plants of Baja California, Mexico' by Rebman, Gibson, & Rich. The latter indicates:

''This rare native species occurs at higher elevations in the Sierra San Pedro Martír of northwest Baja California in our region.''

So it seems it is not known from elsewhere in Baja California...and it's also not recorded from Alta California. However it does occur in every other western US state and east to TX and MI, as well as from British Columbia to Ontario (see map here). The FNA treatment for this species is here.