The purpose of this Excel workbook is to graphically demonstrate a very common but often misunderstood dynamic that exists in most jails in the United States. In most jurisdictions, there is a tendency for justice system decision-makers (including jail staff), in their attempts to lower the jail population because of crowding, to focus their attention on the high volume of inmates who are booked into the jail. However, even though a high volume of inmates of a certain type (e.g., persons charged with low-level traffic or misdemeanor crimes) are admitted, they almost always do not consume many jail beds because of their short length of stay. Additionally, most jails experience the much less frequent booking of certain types of inmates who stay for a very long time (e.g., 91+ days). This latter group of inmates often goes relatively unnoticed by jail staff because not many of these inmates are processed through the jail. However, these inmates occupy the majority of jail beds on a daily basis, and thus contribute the most to jail crowding.