Literally. We are kept in high security, prison-like facilities. Everyone has their own cell. Some of us are under lock and key in the solitary-like cell blocks, whilst the rest are kept in... less cramped cells.
The powerful prison guards union, for example, bloats the budgets of state-run facilities, whereas companies like Corrections Corporation of America (CXW) and The Geo Group, Inc. (GEO) hold a pricing advantage by being able to pay guards non-union wages.