Green’s Dictionary of Slang

(US) insignificant, petty.

1930		W.R. Burnett Iron Man 10: She was used to bum hotels, and day coaches, and three-a-day on a tanktown circuit.
1937		E.R. Burroughs ‘Resurrection of Jimber-Jaw’ in Goodstone Pulps (1970) 11/1: You tank-town Romeo – get out and stay out.
1940		R. Chandler Farewell, My Lovely (1949) 31: You would find them in tank town vaudeville acts, cleaned up, or down in the cheap burlesque houses, dirty as the law allowed.
1941		J.M. Cain Mildred Pierce (1985) 489: Every one-horse conservatory, every tank-town university.
1953		J. Thompson Savage Night (1991) 12: What’s a fast guy like you doing at a tank-town teachers’ college?
1979		E. Torres After Hours 41: The bullring was tank town.
1983		R. Price Breaks 369: He’d have to wind up teaching in some small tank-town college somewhere.