Commentators and politicians often compare crime in cities and states to one another. When it comes to Chicago, the national narrative often focuses on the murder count. While the sum of murders in Chicago is an important metric, it’s also important to take into account the other influences driving those numbers like population, density, gun laws, policies, geography and economics, reports WTTW. Further complicating national comparisons, all crime isn’t reported, and when it is, it isn’t reported identically across local agencies. Nationally, there were gaps in information in the transition to the FBI's National Incident Based Reporting System (NIBRS), because early responses from local agencies were spotty when compared to its predecessor. Many agencies were slow to adopt the new federal system, if they signed on at all, creating barriers to compare data across years or to estimate figures for some states.
“The very first thing we need to understand is this is not designed to be a mandatory, accurate reporting system,” said Adam Wandt, assistant professor at John Jay College of Criminal Justice. “This is a voluntary system that helps us understand the general state of crime in the nation.” The NIBRS system is supposed to count all crimes in an incident, rather than just the top charge as was done by the past system. However, a lot of crime is still missed, including those that go unreported. Homicides can be tracked through medical examiners’ offices and other sources, allowing these figures to be verified independently. It’s more difficult to substantiate other violent or property crimes. Violent crime was reported by victims at a rate of 45.6% in the 2021 National Crime Victimization Survey. Rape and sexual assault were reported in 21.5% of victimizations. Property crime was disclosed at an even lower rate. Some departments refuse to take reports on specific crimes, Wandt said. Some categories of crime are not counted by the FBI, Wandt said, making certain analysis difficult. Violent crime can also be normalized by population. Chicago finished below the rate of Rockford and Peoria among the largest cities in Illinois in 2022. Chicago reported 695 murders in 2022, while Peoria saw 24.