Green’s Dictionary of Slang

1. (US tramp) the Chicago, Burlington and Quincey Railroad.

1899		J. Flynt Tramping with Tramps 48: Seldom has there been such a laugh on the ‘Q’ railroad as they gave on seeing him.
1926		N. Klein ‘Hobo Lingo’ in AS I:12 652: Q—The Chicago, Burlington, and Quincy Railroad (carries bums quickly).
1931		Irwin Amer. Tramp and Und. Sl. 153: Q. The Chicago, Burlington and Quincy Railroad, a system which serves much of the farming territory in the Western Central area, and largely used by ‘bindle stiffs,’ ‘hobos’ and ‘boomers’ during harvest time.

2. (US Und., also the Q) San Quentin prison, in California.

1930		(con. 1890) G. Milburn ‘A Convention Song’ in Hobo’s Hornbook 26: There was Boogie Sam and Biff ’n’ Bam, / And a little punk from Q.
1952		C. Hamilton Men of the Und. 243: Lowrie was sent up to ‘Q’.
1963		M. Braly Shake Him Till He Rattles (1964) 83: Okay, you just play it like that, and there’s no way you’re going to stay out of Q.
1977		E. Bunker Animal Factory 12: ‘You might miss Q and Folsom,’ a potbellied old con said.
1989		J. Morton Lowspeak.
1990		(con. early 1950s) J. Ellroy L.A. Confidential 453: Johnny wants jail guys out. Q train.
2005		D. Nelson Inner Piece 37: The Graybar Hotel. The Joint. Stir. ‘Q’. The Pen. Most of these names he’d heard before.
2020		D. Winslow ‘The San Diego Zoo’ in Broken 155: ‘A repeat offender like you should be in the Q’.

3. (Aus.) The Queensland Railway.

1924

L. O’Neil ‘The Q.’ in Dinkum Aussie and Other Poems 19: The Queensland Railway dances [...] The dingo halts his roaming, / To see the headlights of the Q / Far-shining in the gloaming.