Photo: Michael Tercha/Chicago Tribune

Police investigate the scene on 99th and Halsted streets Tuesday, July 2, 2013 after a man selling newspapers to drivers was shot and killed around 6 a.m.

Just before the long, deadly Fourth of July weekend, the Tribune web apps team produced a remarkable map: shooting victims in the city in 2013, along with some data from 2012. Just looking at homicides is incomplete; as I've written about before, the line between a homicide and a shooting can be a very fine one, with just a couple inches separating a high-profile fatality from an obscure statistic, or something as simple as caliber, whichever gun the shooter happened to get his hands on.

So it's excellent to see the geography of it. As usual, Austin has the most victims: 70 this year, a bit behind 2012's pace (162 total). But Austin is also Chicago's biggest community area, with 98,000 people as of the 2010 Census. Englewood and West Englewood have worse per capita stats: Englewood has 30,000 people and 50 shooting victims in 2013; West Englewood has 35,000 people and 47 shooting victims this year. They're part of a particularly dangerous belt that runs from Chicago Lawn (55k people, 45 shooting victims), Auburn Gresham (50k people, 47 victims), Greater Grand Crossing (32k people, 49 victims), and South Shore (50k people, 52 victims).

Here's a detail of that area.

A few days ago I spoke with Northwestern prof Bill Savage about depictions of Chicago; he'd recently had Sun-Times reporter Frank Main in to talk to his class, and one of the things Main said was that Chicago, despite it regularly showing up in the news for its violence, is mostly quite safe. Take Ashburn and West Lawn, two South Side neighborhoods forming the light-blue "L" that Columbus Avenue runs through. They have a combined 14 victims in 2013, with a combined population of about 75,000. Hot and happening West Town, where I sort of live and feel totally safe walking and biking at all hours, has 81,000 people and 14 victims so far. Humboldt Park, where I also sort of live—I'm kind of on the border, technically Humboldt but culturally UKV—has 56,000 people and 46 victims so far, a slightly slower pace than last year (109 victims).

There's also a year by year comparison of shootings. Things have been a bit better most months this year, except for March, which was much, much better.

The high temperature in March 2013 was 60 degrees. The average high temperature in March 2012 was 63 degrees; the mean temperature in March last year was 20 degrees higher. The data, and the research, point to temperature being an important influence.