Green’s Dictionary of Slang

(US) a native of Vermont.

1772		Connecticut Courant 22 Aug. n.p.: Captain Warner’s company of Green Mountain Boys [...] fired three volleys of small arms in concert .
1811		Niles’ Reg. I 133/2: Three or four thousand ‘Green mountain boys’ employed to look towards Canada [DA].
1865		G.A. Sala My Diary in America I 116: The ‘Green Mountain Boys,’ as the Vermonters are pleased to call themselves.
1871		Semi-Wkly Louisianan 31 Aug. 1/3: The Nicknames of the States [...] Rhode Island, gun flints; South Carolina, weasels; Tennessee, whelps; Texas, beefheads; Vermont, green mountain boys; Wisconsin, badgers.
1885		North Amer. Rev. Nov. 433: Among the rank and file, both armies, it was very general to speak of the different States they came from by their slang names. Those from [...] Vermont, Green Mountain Boys.
1909		J. Ware Passing Eng. of the Victorian Era.
1942		R. Peattle Friendly Mountains 67: They have an ironic sense of humor, a trait which was in the Green Mountain Boys perhaps more volatile than it is now .