In Chicago, Illinois, during the last weekend of September, 53 people were shot and injured and another four were shot and killed. The numbers should have marked an aberration for the month, but they did not. The weekend before, 45 were wounded and eight killed. According to the Chicago Tribune, it was the first time in four years that the city had recorded over 50 gunshot victims on consecutive weekends. The first half of the month was not much better. On the weekend of September 12, gun violence left 30 injured and two dead. The prior weekend, over the Labor Day holiday, it led to 46 injuries and eight deaths.

Among American crime reporters, summer is regarded as the high season for gun violence. When it ends, a reprieve is expected. But in Chicago, this September is merely a continuation of the violent months that preceded it. The past two weekends were almost indistinguishable from the period that encompassed Independence Day celebrations, when, between the evening of July 2 and the morning of July 6, gun violence caused 55 injuries and ten deaths.

Chicago’s rise in gun violence has been well documented, but the numbers remain striking. By the end of the summer, there had been 1,625 shootings in the city — a 17.4 percent increase from the previous year. But comparing September 2015 to Septembers past creates a startling picture. According to an analysis of media reports, there were 196 weekend shootings this month. In 2014 there were 124. And in 2013 there were 71. (During the Septembers of 2013 and 2014, Labor Day fell at the end of August. But even if you factored in those numbers, effectively adding a fifth weekend for either year, the weekend totals would still be greater.)

These tallies amount to a startling departure. In 2013, there was an average of 17.5 shootings per September weekend in Chicago, with 15.25 injuries, and 2.5 deaths. In 2014, the number rose to an average of 37 shootings per weekend, with 27 injuries and four deaths. And in 2015, the average total jumped to 49, with 43.5 injuries and 5.5 deaths.

“These are numbers you expect from a war zone, not an industrial city” Cook County Commissioner Richard Boykin tells The Trace. Boykin is pushing for the city to create a gun violence czar, who would encourage communication between Chicago’s various law enforcement agencies. “Without it, I expect these levels of violence are going to continue,” he says.

The Trace reached out to a dozens of academics who study violent crime in Chicago, but most could not offer an explanation for the increased violence over weekends, and several cautioned against extrapolating too much from a small data set. City law enforcement sounded the same note. Others could only offer informed speculation.

“We’re definitely seeing an uptick,” says Colleen Daley, the executive director of the Illinois Council Against Handgun Violence. “Is there something going on between gangs we aren’t aware of? That information hasn’t come out yet.” She thinks the fact that the city has completed its third month without a budget could be a factor. “The situation is hurting social service programs,” she says.

One Chicago criminologist, Dr. David E. Olson, a professor at Loyola University, suggested the trend may have to do with continued warm weather patterns. “This September was one of the warmest on record,” he tells The Trace.”There’s clearly a correlation there. Lots of people are still outside on the weekends.”

In August, The Trace interviewed Dr. Gary Slutkin, a renowned epidemiologist who believes violence acts like a contagion, which means a violent summer would naturally beget a violent fall. “The greatest predictor of violence is exposure to a preceding event of violence,” he explained. “We…know there’s an underlying process that causes this to happen: There are neurons on the brain that cause copying, which is the principle way people pick up all kinds of behavior.” To follow Slutkin’s thinking is to stop measuring gun violence in seasonal shifts, and instead look at it as a disease that continues to proliferate.

[Photo: Flickr user Tony Webster]