Emerging Adults in Illinois: Recent Trends and Patterns in Arrests and Prison Sentencing

Recently, Loyola’s Center for Criminal Justice (CCJ) was invited to present at the Summer 2024 quarterly meeting of the Illinois Juvenile Justice Leadership Council, on the topic of “emerging adults”—those between 18 and 24—in the Illinois criminal justice system. This research brief summarizes that presentation, which was based on new analyses of Illinois arrest and prison admission data pertaining to emerging and older adults.

There are good reasons for criminal justice policy-makers, practitioners, and advocates to focus on the emerging adult population. First, because they are cognitively different from older adults: despite their having reached social and legal adulthood, research has shown that this age group still tends to exhibit immaturity when it comes to impulsivity and decision-making.

Because criminal conduct may be a consequence of that immaturity, emerging adults are arguably less blameworthy than older offenders. Moreover, since their brains are still developing, they may be more amenable to change.

Previous CCJ reports have explored the overall impact of emerging adults on the Illinois criminal justice system, and inventoried programs and services available to justice-involved emerging adults nationally. For this report, we analyzed more recent data on arrests and prison admissions in Illinois, to see how the justice system’s handling of emerging adults may be changing over time.

In particular, for many of our analyses, we compared the most current available arrest and sentencing numbers with data from 2010 and before. The year 2010 was chosen because it marked the beginning of a series of significant legal, administrative, and practice changes in Illinois—including amendment of jurisdictional age laws,

expanded funding for alternatives to incarceration,

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and a gradual shift in routine sentencing practices

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—which might be expected to have some impact on the handling of emerging adults.

Arrests and Arrest Rates

When arrests for all offenses were examined over time, substantial decreases were seen for both emerging adults and older adults between 2010 and 2023. However, the decrease in arrests among emerging adults—a 67% drop overall—was twice as large as the 33% decrease among older adults.

The arrest decline was continuous for both groups, although of course there were steeper drops in arrests during the COVID years 2020 and 2021, likely as a result of pandemic-related changes in policing practices (e.g., fewer traffic stops) and declines in specific types of criminal activity (e.g., fewer burglary offenses due to potential victims staying at home).

When only arrests for felony-level offenses were considered, there was a substantial decrease among emerging adults—a 47% drop in arrests between 2010 and 2023—and almost no change in the number of arrests for older adults.

This pattern of total arrests involving emerging adults decreasing more than arrests for older adults was also evident when arrests for specific kinds of crime were examined. For example, the combined total arrests for violent crimes (e.g., battery, assault, robbery) involving emerging adults fell 56% between 2010 and 2023, compared to a 19% decrease among older adults. Similar patterns were seen in arrests for property crimes (e.g., theft, burglary) and drug-law violations (excluding cannabis offenses).

The one crime category that has seen increases in arrests since 2010 was weapon offenses, which primarily involve the illegal possession of a firearm.

Arrests for weapon offenses increased 65% for emerging adults, but the increase for older adults was even larger (up 116%).

Another way to look at arrests for emerging adults is to calculate per capita arrest rates, which take into account the number of people in the population at risk of arrest. In 2010, the arrest rates for emerging adults in Illinois followed what had been a consistent historical pattern, in being far higher than those of 25-44 year-olds.

For most categories of crimes, emerging adult arrest rates were double those of the 25-44 year-old age cohort. For example, the arrest rate for felony-level offenses among emerging adults was 2,402 per 100,000 in the population, compared to a rate of 1,292 for 25-44 year-olds.

However, because emerging adults experienced much larger decreases in total arrests and arrests in specific crime categories than older adults during the 2010-2023 period, this historical difference in arrest rates appears to have vanished. After having been arrested for felony offenses at almost twice the rate of older adults in 2010, by 2023 emerging adults’ felony arrest rate was only 5% higher than the older adult rate (1,401 vs. 1,324 per 100,000).

The same was true across almost all crime categories. For example, in 2010 the property crime arrest rate for emerging adults was more than double that of older adults; by 2023, the difference was only 11%. The emerging adult arrest rates for violent crimes and non-cannabis drug-law violations in 2023 were actually lower than those of older adults.

There was one exception to this pattern. Arrest rates for weapon violations (again, primarily the illegal possession of a firearm), rose for both groups during the 2010-2023 period, but in 2023, the emerging adult arrest rate remained twice as high as the older adult rate.

Prison Sentencing

Loyola’s Center has elsewhere documented a substantial drop in the use of prison in Illinois in recent decades, and has posted an Illinois Sentencing Dashboard enabling users to explore the decline. Some of this trend can be explained by the reduction in felony arrests, of course, which has resulted in fewer felony court filings and convictions—and so fewer people who could be sentenced to prison. And this effect was sharpened during the COVID period, when court processing as well as law enforcement activities were substantially curtailed.

But Illinois has also seen a reduction in reliance on prison sentences, even for those convicted of felonies. During the same period that felony convictions declined, the likelihood of a prison sentence following conviction also declined, reflecting a broader use of probation in Illinois. Where probation is an option,

most people convicted of a felony receive probation sentences, and the proportion of probation to prison sentences has grown. In 2010, for example, 55% of all people convicted of Class 1 through 4 felonies were sentenced to probation; by 2023 that had increased to 66%.

The trend away from prison sentences has been even more marked for emerging adults: the number of emerging adults receiving prison sentences declined 72% between 2010 and 2024, compared to a 46% decrease in prison sentences for older adults.

Overall, about 17% of those sentenced to prison in 2024 were emerging adults, compared with 28% in 2010.

The number of 18- to 24-year-olds sentenced to prison in 2024 was the lowest for any non-COVID year in more than 3 decades.

In addition to the overall decrease in sentences to prison involving emerging adults, there have also been substantial changes in the nature of the offenses for which they are being sentenced. The most significant change has been a decreasing share of emerging adult prison sentences involving drug-law violations and property crimes, and an increasing share accounted for by violent crimes and firearm possession offenses. In 2000 and 2010, more than one-half of emerging adults sentenced to prison had been convicted of property crimes and drug-law violations, and less than 10% had been sentenced for a firearm possession offense. By 2024, only 20% of emerging adults were sentenced to prison for property crimes and drug law violations combined, but nearly 40% had been sentenced to prison for a firearm possession offense.

The share of emerging adults sentenced to prison for violent crimes also grew—from 34% of all emerging adult admissions to prison in 2010 to 43% by 2024.

Among those currently in prison for murder, 35% were emerging adults at the time of admission.

Demographically, almost two-thirds of emerging adults sentenced to prison in 2024 were Black; this proportion has increased since 2010, when 58% of emerging adult prison admissions were Black. Cook County imposed about half of the state’s total emerging adult prison sentences.

Post-Prison Recidivism

A consistent pattern in criminological research is that those who are younger tend to have higher recidivism rates than those who are older, and recidivism among those released from prison in Illinois follows this general pattern. An analysis of 30,168 individuals released from Illinois prisons in 2018 and 2019 found that 45% were not arrested for any crime within 3 years of their release, 30% were arrested for a non-violent crime, and 25% were arrested for a violent crime. Among those released from prison who were still in the emerging adult age range, however, 36% were arrested for a violent crime after their release from prison, compared to 26% among those 26-40, and 14% of those 41 or older.

Discussion

All of the above analyses are for the state of Illinois as a whole. It’s important to remember that trends and patterns in arrests and sentencing vary from region to region, and even from county to county. And in Illinois, state totals are heavily impacted by Chicago: overall, about 44% of all arrests occurred in Cook County, which includes Chicago. In 2023, Cook County imposed about 40% of all prison sentences in the state.

With that caveat, disaggregating statewide arrest and prison sentencing data to separate emerging adults from older adults is a useful and revealing exercise. Clearly, there has been a broad and substantial decrease in the number of emerging adults arrested in Illinois over the past 14 years, at least at the state level. And the fact that the decline in arrests has been so much steeper for emerging adults than older adults suggests that something different is happening with emerging adults, demanding further investigation. Is it a matter of differences in emerging adults’ involvement in criminal activity, or differences in the detection of their criminal behavior, or differences in the justice system’s responses to their criminal behavior, or some combination of all three?

Similarly, the substantial increase in arrests for weapon offenses, primarily the illegal possession of firearms, could reflect changes in behavior (for example, more gun-carrying), changes in police priorities (for example, a crackdown on firearm possession to prevent violence), or both.

In any case, the consequences of the changes outlined here are clearly being reflected in Illinois’ prison population. There has been a large and sustained decrease in the number of both emerging adults and older adults being sentenced to prison, but the number of emerging adults receiving prison sentences has fallen much more sharply.

Methodology

Aggregate data on arrests were provided by the Illinois Criminal Justice Information Authority (ICJIA) through their access to the Illinois State Police’s Criminal History Record Information (CHRI) system. All of the analyses presented here use the “person-level” data for arrests. Information regarding prison admissions was provided by the Illinois Department of Corrections. To estimate the age of individuals when they were arrested for the offense that resulted in their sentence to prison, the age at custody was calculated—that is, their age when they were detained pre-trial for the offense that resulted in their prison sentence.