Green’s Dictionary of Slang

(US) a fake bankroll, a note of a high denomination around a large number of notes of smaller denomination; by ext. a spectacular trick.

1913		Sun (NY) 27 July 40/1: Everybody around the joint flashes a million dollars — it looks like it, with an Abe Lincoln on the outside of a Michigan bankroll. You’re jerry to the Michigan?
1914		Jackson & Hellyer Vocab. Criminal Sl. 58: michigan [...] A spectacular ruse; a deceptive appearance, as a fake bank roll.
1929		W. Winchell Your Broadway & Mine 24 May [synd. col.] In the old days if you flashed a lot of one-dollar bills you referred to it as a ‘Michigan bankroll’.
1934		J.L. Kuethe ‘Prison Parlance’ in AS IX:1 27: Michigan-roll. A bankroll made up of stage money with a genuine banknote wrapped around the outside.
1939		W. Winchell On Broadway 23 June [synd. col.] Beverly Smith (the ace scribe of his day) outfitted himelf in a ‘hayseedy’ suit, and, armed with a Michigan bankroll, sauntered through the Island.
1949		Monteleone Criminal Sl. (rev. edn).
1950		Goldin et al. DAUL 138/1: Michigan bankroll. 1. A roll of paper with a bank note of large denomination wrapped around the outside to simulate a bankroll — for use in swindling. 2. A roll of single bills wrapped inside a bank note of large denomination to be exhibited for effect.
1961		J. Scarne Complete Guide to Gambling.
1976		R. Sabbag Snowblind (1978) 52: He pulled out a phony bankroll to pay for it – a Michigan, two hundreds on top and fifty ones underneath.
1997		Simon & Burns Corner (1998) 320: Arm him with a Michigan roll faced with a $100 note, and he was good enough to go on the road, taking off jewelers up and down the coast.
2012		W. Keyser ‘Carny Lingo’ in http://goodmagic.com 🌐 Michigan Bankroll — A bankroll with a few genuine dollar bills on the outside, but just blank paper on the inside. Or a bankroll with a high note outside covering many $1 bills inside.