The majority of offenders convicted of felonies and sentenced to more than a year of incarceration are transported from the county jail to the state prison within a few days or weeks of conviction. County jails are used to house those waiting for trial, serving time for a misdemeanor, or on hold for other states. But sometimes exceptions are made. Depending on the county, the severity of the crime and the jail policies, an inmate might be allowed to stay at county jail if his primary family member is severely disabled or terminally ill. The purpose of this decision is to make it more physically feasible for the disabled or terminally ill family member to have visits with their inmate family member. It is not unusual for state prisons to experience overcrowding. Typically, they just double up the inmates, but if the overcrowding becomes severe, the prison stops accepting new inmates of non-violent crimes until they can free up some beds. In this case of overcrowding, an inmate can possibly spend many months in county jail without being transferred to a prison. Once in awhile a judge might decide an offender will be better served by remaining in county. For example, the offender has a drug addiction and the court wants to send him to a residential rehabilitation facility before sending him to prison. How long the inmate remains in county jail will depend on how long it takes for a bed to become available at rehab. You may be interested in Reprieves and Commutations info