Exploring the link between the baby boom and aging prisoners

America’s prisoners are getting older and concern over this problem is rising. Not only are inmates over the age of 50 the fastest growing prison population in the U.S., the increased need for healthcare services among this group makes them more costly to house. In fact, an estimated $16 billion dollars is spent annually to house and care for older prisoners. Moreover, debate and uncertainty over what forces are driving this growth has made it difficult to form optimal policy responses.

By and large the prevailing explanation has been that harsh sentencing laws have caused an accumulation of older prisoners; however, an estimated 72% of older inmates incarcerated in 2011 have been admitted to prison since 2000. New research is now showing that a significant explanation is the rising age of admission to prison – from 2000 to 2011, the average admission age in a 17 state sample has increased by 14 months (from 33 to 34.2 years old).

Fig. 1. Annual Prison Admissions Growth from 2000 - 2011 in 17 States

Fig. 1. Annual Prison Admissions Growth from 2000 – 2011 in 17 States

But what is driving this rise in admission age? One explanation is that the general population is simply getting older. Consider Figure 1 as an illustration. It shows the average annual growth of the prison population (the boxes) contrasted against the same growth for the general population (the dashes) in 17 states. There is an obvious concordance between the growth rates of these two populations broken down by age group.

We take this comparison a step further by conducting data simulations to estimate the sizes and ages of prison populations (in 2011), where only the population age distribution has changed (i.e., holding constant all other factors affecting prisoner age). By comparing simulated changes to observed changes in reality, we get a representation of how much population aging explains actual changes.

The results are provocative. Figure 2 shows the correspondence of changes between observed conditions (the solid bars) and simulated conditions (the patterned bars) in the estimated number of prisoners. For the youngest age groups, population aging explains little; other factors appear to better explain the prison population change. However, for older age groups, population aging alone contributes a sizeable increase to the predicted population. For offenders between the ages of 50 and 64, the overall simulated impact of population aging is 27% of the observed change, ranging between 19% and 52% depending on the age group.

Fig. 2. Observed and Simulated Changes in Prison Population Totals Relative to the Steady State Prison Population in 2011

Fig. 2. Observed and Simulated Changes in Prison Population Totals Relative to the Steady State Prison Population in 2011

The strength of association between population aging and older inmate populations implies that major demographic events like the baby boom play a significant role in shaping prison populations. It also suggests important lessons for the future. First, the current trend is in part a natural artifact of history. Since individual states can do little to change macro trends in aging, focusing efforts on reducing overall inmate costs and health care costs to address the aging issue may be a first-best solution. The problem should begin to reverse as trends in demography also reverse.

Second, although population aging is an important element, there remain other important explanations. Understanding the impact of other social factors, economic forces, sentencing policies, and enforcement strategies, is of paramount importance to devising appropriate policy responses.

Finally, “permanent” policy changes meant to reduce the inflow and increase the outflow of older inmates will persist even as this problem naturally subsides with the passing of this birth cohort, and a negative consequence may be that the proverbial pendulum swings too far in the other direction and unintended consequences emerge in the long run. To avoid this, states should consider integrating sunset provisions into new policies meant to address this problem.



The Growth of Older Inmate Populations: How Population Aging Explains Rising Age at Admission.
Luallen J, Cutler C
J Gerontol B Psychol Sci Soc Sci. 2015 Aug 25


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