I sent a tweet yesterday regarding murder rates in various cities in January 2017 that I wanted to delve a bit deeper into because there’s a lot to unpack with it.

The tweet said the following:

Approximate murder rate per 100k for January 2017:

New Orleans – 5.59

Baltimore – 5.15

St Louis – 4.42

Chicago – 1.87

There are a number of nuggets and interpretations to this data and all of them are correct. I put the numbers together by gathering murder counts in those four cities from various sources (Chicago here, Baltimore here, St Louis here, New Orelans from my personal count). Rates were calculated by dividing murder counts by 2015 FBI UCR population figures.

The first reaction I had when putting together was surprise that New Orleans had a worse January in terms of murder rate than Baltimore which had over a killing per day for a month. New Orleans is on pace for a very bad year, and while it’s early in the year, the level of gun violence in the city appears to have increased dramatically.

The second thing that jumped out was the degree to which weather can play a role. Chicago had a worse January in 2017 than in 2016 yet the city’s murder rate paled in comparison relative to warmer cities Baltimore and New Orleans. The average temperature in Baltimore was six degrees higher in January 2017 than January 2016.

The below graph shows the percent of Chicago homicides from 2001 to 2016 that occurred in each month. As you can see January is the second slowest month in Chicago with things peaking in July. This means you can’t really read too much into Chicago’s January.

chicago-month

The third and final thing that jumped out was the depressing realization that New Orleans has eclipsed the 2016 national murder rate in just one month. Last year there were somewhere between 5 and 5.3 murders per 100,000 nationally depending on how big the national jump was. New Orleans was above that in just January and Baltimore came close to equaling it.