Green’s Dictionary of Slang

(US) illicitly distilled whisky; thus blockader, a distiller.

1867		J. Scott Partisan Life 195: The parson had taken about half a pint of ‘blockade,’ and did not care the snap of a finger for the reproachful looks.
1874		Waco Dly Examiner (TX) 31 mar. 2/3: An old blockade whiskey distiller, who had been making whiskey in contempt of the revenue officers.
1883		Zeigler & Grosscup Alleghanies 141: In the wilderness, we would be taken for revenue officers and, as such, shot on sight by blockaders [DA].
1886		St Paul Dly Globe (MN) 28 Nov. 15/2: The young man went to the judge and asked him if he didn’t want some good blockade whiskey.
1897		Roanoke Times (VA) 10 Sept. 3/2: Lots uv swappers begin their business on nothin’ mor’n a jug uv blockade whiskey.
1913		M.W. Morley Carolina Mountains 66: That important beverage, variously known as ‘corn-juice,’ [...] ‘blockade,’ ‘brush whiskey,’ and in the outer world, ‘corn-whiskey’.
1919		Central Record (Lancaster, KY) 11 Dec. 6/3: Old Paint Rock was always a pretty good market for ‘blockade whiskey’.
1929		L. Axley ‘‘Drunk’ Again’ in AS IV:6 440: Some names for intoxicants of various grades and potencies are: blockade—common in the Southern mountains.
1943		National Geographic Mag. Dec. 766/1: The preacher converted the ‘king’ of the ‘blockaders’ (moonshiners) [DA].