Green’s Dictionary of Slang

(US teen) any youth unaffiliated to a street gang.

1959		E. De Roo Young Wolves 71: ‘I’m a coolie, Cliff.’ ‘Who put ya up to it?’ ‘You know I don’t belong to any gang, Cliff.’.
1960		E. De Roo Big Rumble 9: Even as a non-gang member, a coolie, he knew the mark of the Spiders.
1965		S. Yurick Warriors (1966) 102: Are you studs going to let that coolie insult my honour?
1967		P. Thomas Down These Mean Streets (1970) 49: I hear you 104th Street coolies are supposed to have heart.
1967		in S. Harris Hellhole 123: Cora May sold most of her cigarettes to ‘coolies,’ girls who weren’t auxiliary gang members.