Reflections on Declining Crime in Chicago: Executive Summary

This report examines recent crime trends in Chicago. It describes what happened in the city,
and addresses the issue of why crime has declined so precipitously. The report draws upon
the conclusions of research on the drop in crime and data from Chicago for the 14-year
period 1991-2005. The conclusions challenge some popular explanations for declining crime
– for example, that it was due largely to growing prison populations, an increase in the
number of police, or the city’s improving economic fortunes. However, in many instances
there is not enough information to adequately test potentially important explanations for the
decline of crime in Chicago. Where appropriate, I have therefore added my own judgment
about these matters to the mix of data and research, and in the conclusion I advance a
scenario which might account for the post-1991 drop in crime in Chicago.

Crime peaked in Chicago in 1991, then began its long decline. By 2005, violent crime
declined by 59 percent. The largest decline was in robbery, which went down by 64 percent.
Homicide dropped by 52 percent and aggravated assault by 54 percent. Combining all
offenses in which a firearm was used in some way, there was a 64 percent drop in the level of
gun crime in Chicago. In the property-crime category, auto theft and burglary were both down
by 52 percent. An important feature of the decline in crime in Chicago is that it has been
extremely widespread. Across the city’s 279 police beats, property crime went up in five and
down in 274 beats,  while violent crime went up in 16 beats and declined in 263 beats. Crime
declined most dramatically in predominately African-American communities. For example, gun
crime dropped by 65 percent in predominantly African-American areas, and it was also down
by 60 percent in heavily Latino beats. By the mid-2000s, Chicagoans in most neighborhoods
had seen tremendous improvement in the quality of their lives. In a “what if” world in which
crime had not dropped, but had instead remained at its 1991 level, by the end of 2005 an
additional 3,100 people would have been murdered. There would have been 16,000 more
sexual assaults, 250,000 more burglaries, and 222,000 more auto thefts, if crime had not
dropped as it did.

But why did crime drop so precipitously? There has been a great deal of debate about this
question, for Chicago was not the only city experiencing a substantial drop in crime during
the same period. Explanations for the decline in crime range from “a” (alcohol use, which is
down) to “z” (zero tolerance policing). Sections of the report examine most of the serious
claims, matching them up against trends in Chicago. They conclude that:

•        The decline in crime was not due to demographic changes, nor to improving economic
conditions for families or young people.

•        Not much of the decline in crime could be attributed to prisons. Trends in incarceration
cannot explain the magnitude of crime decline during the 1990s; crime continued to drop
after Illinois’ prisons stopped growing after 2001; and after 1999 Chicago’s incarceration rate
declined along with its crime rate.

•        The decline in crime was not due to the deterrent effects of going to jail. The Cook
County jail also expanded during the 1990s – and for several years after prisons stopped
growing – but not enough in light of the probably limited deterrent impact of short spells
behind bars.

•         Not much of the decline in crime could be attributed to the sheer number of police
officers. Police are expensive, and their numbers did not grow fast enough or long enough.

•         Declining crime was not due to the decreased frequency with which Chicagoans carry
guns; non-gun crime declined just as fast and far.

•         The decline in crime was not linked to any reduction in the influence of the city’s large
and violent street gangs. Non-gang crime declined consistently, while gang crime traced an
up and down course in response to volatile intra-gang dynamics and a shifting business

•         The decline in crime was not due to a declining crack cocaine market. Cocaine-related
arrests went up rather than down, while emergency-room treatment for cocaine-related
episodes were as frequent in 2005 as they were in 1991. Except for powder cocaine, drug
markets continued to flourish even as crime dropped. Homicide associated with the drug
trade went up and down, but it was a very small proportion of all violence and it was non-drug
violence that dropped consistently.

•        Crime did not drop city-wide because of the demolition of public housing. Crime rates in
and around public housing properties dropped faster than they did in the remainder of the
city. Those rates always constituted a small percentage of all crime in the city, however, and
could not account for its sweeping downturn.

•         Improving security in the schools could not explain the city-wide decline in crime.
School-based assault did not decline; rather, it skyrocketed in the 2000s. By 2005,
aggravated assault in and around schools made up almost 11 percent of the city’s total.
Other kinds of school crime – which are down – constitute just a small percentage of the city
total, and could not account for the dramatic decline in crime.

•        While there is evidence that “smarter” policing impacts crime, there is no evidence that
police in Chicago “got smarter” at a pace matching the decline in crime. Any effects of
community policing could not have been felt until the second half of the 1990s, and the police
department’s information-driven crackdowns on drugs and guns did not begin until the 2000s.

•         Strengthening community factors were linked to more rapid declines in beat-level
crime, but it has not been clearly demonstrated that, over all, enough communities in Chicago
have grown strong enough to account for generally declining crime. Decades of
criminological research have established the importance of community factors such as the
strength of family controls, the depth of informal bonds among neighbors, and the organized
crime prevention efforts of neighborhood groups. But little is known about whether these
factors grew stronger or weaker during the 1990s and 2000s, nor how they might have been
affected by community policing.

The report also reviews claims about the decline in crime for which there are little or no data
for Chicago. These include alcohol consumption, which has been on a nationwide decline at
the same time that violent crime has subsided; the impact of abortion policies on child
welfare; “tipping points”; and cultural shifts. There is evidence of a quickening pace of
neighborhood economic vitality during the 1990s and 2000s, but it is unclear is whether this
is a cause or a consequence of the drop in crime.

It is most plausible that the roots of the crime drop in Chicago lie in a mix of the factors
described here. Some or many of them may have been working in concert to reduce crime,
each contributing something to the end result. It is also quite possible that the effects of
these factors may have waxed and waned in significance over this substantial period of time.
Some may have contributed to the drop in crime early on, and others later. As the length of
the great post-1991 decline in crime extends, it is likely that combinations and reinforcing
mixes of factors are at work, rather than One Big Thing. The paper describes one plausible
crime-drop scenario for Chicago that involves a mix of law enforcement and community
factors. The leap in incarceration rates during the early 1990s could have played a role in
crime decline, if prison had larger-than-average effects during it’s early expansion. The
effects of community mobilization around community policing could have been felt by the
latter half of the 1990s, while the police department became visibly “smarter” and well
managed early in the 2000s. The report concludes with a brief discussion of the comparative
costs of interventions designed to further the drop in crime, a necessary component of any
comprehensive policy review.