Funnily enough, this was addressed directly in the comic with the Morlocks. The mutants unable to pass and were living in the sewers under New York.
X-Men #169 to their ultimate elimination in the Mutant Massacre in #210-214, X-Factor #9-11, and New Mutants #46. Also touched on Thor, Power Pack and Daredevil.
Funnily enough, this was addressed directly in the comic with the Morlocks. The mutants unable to pass and were living in the sewers under New York.
X-Men #169 to their ultimate elimination in the Mutant Massacre in #210-214, X-Factor #9-11, and New Mutants #46. Also touched on Thor, Power Pack and Daredevil.
https://en.m.wikipedia.org/wiki/Morlocks_(comics)
https://en.m.wikipedia.org/wiki/Mutant_Massacre