Green’s Dictionary of Slang

from can to can’t phr.

also from can’t to can’t
[i.e. can to can’t see or, longer ,from can’t see to can’t see, i.e. pre-dawn to post-dusk]

(US black) a whole day.

[US]S.C. Adams Jr. interviewee q. in Adams Thesis in Gordon & Nemerov Lost Delta Found (2005) 280: ‘Down here, don't you know a nigger works from “kin” to “kaint”?’ [. . . .] I just told him that I wasn’t one of them “kin to kaint” niggers .
[US]H. Rap Brown Die, Nigger Die! 19: His aunt worked from can to can’t, and by the time she got home at night she was too tired to bend over the scrub board.
D. Jenkins Dogged Victims 175: [black speaker] ‘I work from can’t to can’t,’ he says of Masters week.
[US]W.D. Myers Won’t Know Till I Get There 156: [B]ack in slav’ry times, you did your can to can’t till you couldn’t do no more [...] you got up as soon as you can see and you be workin’ till you can’t see.
[US]Wolfe & Lornell Leadbelly 101: Angola prisoners worked from ‘kin to can’t,’ which means they labored from the time you could see at dawn until it became impossible to see after dusk .