If you've been following the gun debate in Chicago, what Monica Davey finds in her excellent piece in the New York Times on the origin of the city's guns should come as no surprise. Most come from nearby; half come from out of state; many of those come from the Delta.

More than a quarter of the firearms seized on the streets here by the Chicago Police Department over the past five years were bought just outside city limits in Cook County suburbs, according to an analysis by the University of Chicago Crime Lab. Others came from stores around Illinois and from other states, like Indiana, less than an hour’s drive away. Since 2008, more than 1,300 of the confiscated guns, the analysis showed, were bought from just one store, Chuck’s Gun Shop in Riverdale, Ill., within a few miles of Chicago’s city limits.

Chuck's Gun Shop has come up before, over a surprisingly lengthy timeframe. Frank Main, writing in the Sun-Times last year, found that almost 20 percent of guns recovered in crimes used within one year of purchase came from the store (Main also does a good job of looking into the prevalence of stolen guns used in crimes). Jesse Jackson protested in front of the store in early 2012 and previously in 2007. Back in 1999, Chuck's came up in a lawsuit filed by the city against several suburban gun shops, though Chuck's wasn't one of them:

Among Wilson's purchases were seven guns bought from Chuck's Dolton Gun Shop in Riverdale, authorities said. Chuck's wasn't charged with any wrongdoing, but authorities have previously said that more guns seized by police, including the weapon that killed Officer Ceriale, have been traced to Chuck's than any other gun shop in the Chicago area.

"We are very much aware of Chuck's Gun Shop," Lassar said.

But to bring criminal charges, authorities need sufficient evidence that the shop operator or clerk knowingly sold to a straw purchaser, Lassar said.

Davey's story also includes a map, with a focus on the surprising number of guns that come up the river from Mississippi. It's something I've written about before, but Davey unearths a stat I didn't know that gives it more weight: "In 1970 there were more people from Mississippi [PDF] living in Illinois than in all other Southern states" (more specifically, beyond their birth states).

It's where Chicago got its blues from; now it's where we get our guns from. As Nicholas Lemann reported in the Atlantic years ago (in work stemming from his book The Promised Land), the ties between Chicago and Mississippi run deep:

Because the migrants followed the existing train, bus, and highway routes, black Chicago was populated from the states along Highway 51 and the Illinois Central tracks — Arkansas, Louisiana, and, most important, Mississippi. In the fifties alone Mississippi lost more than a quarter of its black population. It's no wonder that the Delta blues became the Chicago blues in the late forties and early fifties; blacks still sometimes call the South Side "North Mississippi."

And it should come as no surprise, if you're familiar with the politics of the South, that Mississippi has some of the least stringent gun laws in the country. That great Guardian visualization reveals that the Northeast  and Southwest have the tightest gun laws, the Southeast the most lax. The Midwest is somwhere in between, but Illinois's neighbors, Wisconsin, Indiana, and Iowa, are considerably less strict than Illinois. In short, there's a pipeline running from Mississippi to Illinois that leads through states with looser gun laws; one of the nice things about the Times's map is that it really emphasizes how north-south that pipeline is. Here's one from Mayors Against Illegal Guns that puts its in a different perspective (PDF).

Red means "no gun show background checks by unlicensed sellers or purchase permits required."

Mayors Against Illegal Guns also looked at which states export guns used in crimes; Mississippi had the highest number per 100,000 residents (50.3); Indiana came in 8th; Kentucky, another border state, was third. Illinois was 43rd, with 6.9 crime guns exported per 100k residents, and for every gun that originates in Illinois and is used in a crime, more than four originate elsewhere and are used in crimes here (specifically, 844 to 3643 in 2009). In other words, the guns come in; they don't go out.

Related: "Biography of a Gun," in which Chicago's David Bernstein traced one gun used in a crime from source to shooting.