Green’s Dictionary of Slang

(US) a prison.

1908		B. Fisher A. Mutt in Blackbeard Compilation (1977) 125: I sentence you to ten days in the gow.
1940		R.L. Bellem ‘Death’s Passport’ in Goodstone Pulps (1970) 115/1: He [...] wanted to take me down to the gow on an assault charge.
1946		R.L. Bellem ‘Latin Blood’ in Speed Detective Aug. 🌐 Okay, be lippy. I still say you’re all going to the gow.