Prevalence estimates for selected calendar years represent a sum of the contribution of each birth cohort to the total number of adults alive who had ever gone to prison. The number of former prisoners was obtained by subtracting the number of prisoners at yearend (NPS) from the total. Estimates exclude admissions to local jails, due to the absence of data needed to calculate first admissions to jail. (See Methodology for estimation procedures and limitations.) ---------------------------------------------------------------------- +1 in 37 adult U.S. residents in 2001 had ever served time in prison+ The 5.6 million adult U.S. residents who were current and former prisoners, represented an increase of 3.8 million since 1974. At yearend 2001, 2,673 persons per 100,000 adult U.S. residents had ever gone to prison, up from 1,251 per 100,000 adult residents in 1974. Overall, approximately 1 in 37 adult residents in 2001 had ever served time in a State or Federal prison. As a percent of all adults who had ever gone to a State or Federal prison, the number of former prisoners has steadily declined (from 88% in 1974 to 77% in 2001). The decline occurred as the number of adults confined in prison at yearend grew by 1.1 million -- a 6-fold increase. Over the 27-year period the number of adult prison inmates rose from 216,000 to 1,319,000. By yearend 2001, there were 628 prison inmates per 100,000 adult residents, up from 149 in 1974. Between 1974 and 2001 the number of former prisoners living in the United States more than doubled, from 1,603,000 to 4,299,000. Relative to the adult population, the number of former prisoners totaled 2,045 per 100,000 adult U.S. residents in 2001, up from 1,102 per 100,000 in 1974. At yearend 2001, 1 in every 49 adults in the United States was a former prisoner. +Two-thirds of the increase in number ever incarcerated due to rise in first incarceration rates+ Nearly two-thirds of the 3.8 million increase in the number of adults ever incarcerated in prison between 1974 and 2001 occurred as a result of an increase in the rates of first incarceration. In 1974 the number of persons admitted to prison for the first time totaled 44 per 100,000 adult residents. By 2001 the rate had nearly tripled, reaching 129 first admissions per 100,000 adults. Over 40% of the total increase in first incarceration rates occurred between 1986 and 1991. First incarceration rates increased from 73 per 100,000 in 1986 to 111 in 1991. About a third of the 3.8 million increase in the number ever incarcerated occurred as a result of growth in the U.S. resident population. Based on estimates from the U.S. Census Bureau, the number of residents 18 and older increased from 145 million in 1974 to 210 million in 2001. Had the rates of first incarceration remained stable at 1974 levels, the number of adults who had ever gone to prison would have increased by an estimated 1.3 million.