In the U.S. 1930 census Albert Edward Hibbs is listed as being at the Pontiac County Jail, Oakland, Mitchigan, enumeration district 3-71, sheet 26B. Under the heading Occupation it says "Block plant".
What does this mean? Was he an inmate serving a sentence there? Or was he an employee working there, if so, doing what?
If he was an inmate, is it possible to find out anything about his crime or the term of his sentence?