Green’s Dictionary of Slang

(US Und.) a safe-cracker.

1848		Flash Dict. in Sinks of London Laid Open 100: Box mam [sic], a thief.
1891		Emporia Dly Repub. (KS) 28 Apr. 3/2: A safe blower is a ‘peter man,’ ‘box man’ [...] formerly called ‘gopher blowers’.
1903		H. Hapgood Autobiog. of a Thief 120: He was one of the most successful box-men in the city.
1908		A. Stringer Under Groove 13: Here was an old and experienced dip and box man, an airy-handed chevalier d'industrie, an ex-yegg.
1914		Wash. Post 11 Nov. Misc. 3/5: In the argot the ‘box-man’ is a safe-blower.
1926		J. Black You Can’t Win 93: Shorty was one of the patricians of the prison, a ‘box man’ doing time for bank burglary.
1930		E.H. Lavine Third Degree (1931) 224: A notorious safe, or ‘box’ man, was killed recently in the Criminal Courts Building during an attempted escape.
1939		R. Chandler ‘Pearls Are a Nuisance’ Spanish Blood (1946) 105: This box man is going to dump them beads in a hurry.
1949		Monteleone Criminal Sl. (rev. edn).
1950		Goldin et al. DAUL 33/1: Box-man or -worker. A safe-cracker.
1953		T. Runyon In For Life 95: The box men [...] were run-of-the-mill, reasonably skilled men who made big scores seldom.
1966		R.E. Alter Carny Kill (1993) 105: I’m no box man.
1970		‘Red’ Rudensky Gonif 6: I was supposed to be the best box-man in the country.
1971		T. Thackrey Thief 124: He’ll even have a list of what he calls ‘people available’ [...] You know – drivers, box-men.