Green’s Dictionary of Slang

(US campus) rural areas, the countryside (not necessarily rough or unpleasant).

1942		C.R. Bond 2 Mar. in A Flying Tiger’s Diary (1984) 122: I brought him up to date on what had transpired while he was in the boonies.
1961		(con. early 1950s) J. Peacock Valhalla 62: He discovered she had been having an affair with a S/Sgt from Tent Camp Two out in the boonies.
1978		A. Maupin Tales of the City (1984) 124: We get up at some godawful hour of the morning to jog through the boonies.
1983		S. King Christine 284: It was hard work, hitching rides, once you got out in the boonies.
1999		S. Grafton O is for Outlaw (2000) 303: Two guys out in the boonies, gotta be Veetnam.
2006		C. Hiaasen Nature Girl 235: I wouldn’t last very long out here in the boonies.
2015		B. Weber in Chicago Trib. 12 Nov. 44/5: It can be quite helpful in areas with lots of members, not so much out in the boonies.
2021		S.A. Crosby Razorblade Tears 161: ‘Get him out in the boonies and make him tell’.