Prison Populations: A Projection Model

We propose a method for estimating prison populations under a variety of assumptions about sentencing policy and demographic structure. The approach builds on a familiar stochastic model of the individual criminal career. After a validation exercise involving Pennsylvania data, we use the model to make illustrative projections about Massachusetts, Utah and Florida. The results suggest that, while prison populations might stabilize everywhere during the early 1990s, only rarely will this situation signify an end to the growth in prison-capacity requirements.