3. …Because only certain kinds of crime are actually declining.

It turns out that not all crimes have decreased by the same degree.

Daily crimes in 2020 (blue) compared to the previous five-year average (black). The red line at day 80 marks Governor Pritzker’s shelter-in-place order.

In sheer quantity of crime, the biggest reduction has been in theft, followed by narcotics offenses and deceptive practice (which includes things like identity theft, credit card fraud, and counterfeiting). Each of these categories fell by at least 40% compared to the previous five-year average.

Put differently: If you remember from above, in the second half of March, we saw about 200 fewer crimes per day than we would expect. These three categories alone accounted for about two-thirds of the total drop.

There are a few likely explanations for this. First and foremost: Theft is the most common crime in the city to begin with, so we’d expect it to constitute much of the overall drop. On top of that, data reveal that the majority of thefts take place in either businesses (which are now shuttered) or residences (which are now more likely to be occupied, and thus harder to rob). As far as deceptive practice, it’s likely difficult to defraud someone or steal their identity when the victim is not working, shopping, or out in public. And two-thirds of narcotics offenses since 2015 have taken place on streets, sidewalks, or alleys; maybe now drug use and drug sales are moving into private spaces, where they’re much more difficult for police or witnesses to report.

On the other hand, crimes like assault and battery have changed relatively little, dropping by less than 20%.* Again, we can think of a plausible explanation: The data reveal that these crimes already tend to occur in people’s homes quite frequently, and the lockdown order presumably wouldn’t make those at-home incidents any less prevalent.

So how do these category-specific changes translate into the neighborhood differences we saw above?

Focusing on the community areas with the highest “baseline” crime levels, we see that they’re characterized by different kinds of crimes.

Again, most of the decline is coming from three categories: theft, deceptive practice, and narcotics. And we can see here that these crimes are a much bigger deal in some areas than in others. Theft and deceptive practice are especially common in the Loop and surrounding areas, while narcotics violations are quite prevalent in places like North Lawndale, Garfield Park, Humboldt Park, but virtually absent in other neighborhoods.

Broadly speaking, the most significant drops have been in areas where these three kinds of crimes are more prevalent.