What did American Eugenicists mean by "dark-haired hill people"?

by illuminato-x

This article mentions "dark-haired hill people". Is it referring to Alpine people and Scottish Highlanders, who are sometimes called hill-people or someone else?

Relevant passage: "In the process, the movement intended to subtract emancipated Negroes, immigrant Asian laborers, Indians, Hispanics, East Europeans, Jews, dark-haired hill folk, poor people, the infirm and really anyone classified outside the gentrified genetic lines drawn up by American raceologists."

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Question:

my initial thought was hill people="hillbillies," "rednecks" aka the people of places like the Appalachian mountains especially since he uses the term gentrified. I have absolutely no clue if this is true and it probably isn't but it got me thinking:

[start of question]

how did racial theorists deal with "white trash" in America? From the history of white people i remember the lapps always had a conflicted status on the fringe of whiteness but did any of this apply to these american groups of what we consider today to be poor whites?