Green’s Dictionary of Slang

(US) that part of the inner city where racial, social, economic and other tensions are at their height; orig. use in Boston, MA.

1972		G.V. Higgins Friends of Eddie Coyle 87: [of Boston], MA The Combat Zone sounded like there was a war going on there for a while.
1980		N. Algren Devil’s Stocking 136: A combat zone where prostitutes, pimps and johns can frolic freely without let or hindrance by the police [HDAS].
1989		Radford & Crowley Drug Agent 54: At the Combat Zone intersection of Washington and Essex Streets [in Boston] [HDAS].
2010		A. Steinberg Running the Books 308: [They] tried to force them to work as prostiutes in Boston’s Combat Zone.