Green’s Dictionary of Slang

(US black) the American black community, i.e. the status of blacks, governmental statements of equal rights notwithstanding, as regards the larger US world.

1993		Source June 59: We represent the USG.
1995		Onyx f/ Greg Valentine ‘Purse Snatchaz’ 🎵 on All We Got Iz Us [album] To me, USG livin, is one gigantic ring of concealin / Double dealin, drug fiendin, sellin and schemin.