Over the past thirty years the United States has experienced an unprecedented rise in the use of incarceration, with the number of people in prisons and jails increasing from 330,000 in 1972 to 2.1 million today.
This trend is in sharp contrast to that of the preceding fifty years, during which time there was a gradual increase in the use of incarceration that was commensurate with growth in the general population. Between 1920 and 1970 the overall population nearly doubled, while the number of people in prison increased at just a slightly higher pace. However, between 1970 and 2000, while the general population rose by less than 40%, the number of people in prison and jail rose by more than 500%. Potential explanations for this dramatic change in policy have included changing crime rates, politics, demographics, and cultural shifts.
The relationship between incarceration and crime is complex. Researchers have struggled to quantify accurately the degree to which crime reduction is attributable to imprisonment. Among the many challenges associated with the issue are the following: distinguishing between state and national trends; differing measures of crime and victimization; and, assessing various time frames for analysis. In addition to incarceration, studies have identified a range of factors which may affect crime, including general economic trends, employment rates, age, demographics, rates of drug abuse, and geographic variation. This briefing paper provides an aid to policymakers and the public by reviewing what is known about the effects of incarceration on crime.
To read the briefing paper, download the PDF below.