According to Williams et al. (2014). "Closely related to B. flavidus from Europe and Asia. Found in Mountain West from CA and CO, to AK, east to Canadian Great Plains, with a disjunct population in NL. Apparently declining in some parts of its range."
Reference: Williams, Paul, Robbin Thorp, Leif Richardson, and Sheila Colla. 2014. Bumble Bees of North American: An Identification Guide. Princeton University Press.