It is Illinois Gun Owners Lobby Day in Springfield and thousands of pro-gun activists are expected to show up and rally. Tuesday an Illinois House Panel passed a concealed carry measure. Similar measures have stalled in the past, and Illinois is one of only two states that prohibit concealed carry.

But those on the side of gun control are also on the bubble. Chicago Mayor Richard Daley is calling for stiffer restrictions on guns. All of this comes in the wake of last year’s Supreme Court’s decision to strike down the City’s handgun ban.

So how has the new gun regime changed the amount and type of weapons in the city? And how is all of this driving politics around guns? The University of Chicago’s Crime Lab analyzes, among other things, the effect of social policy on crime. Professor Jens Ludwig is director of the Lab and he has studied the social costs of handgun violence. Ludwig is currently a visiting scholar at the Russell Sage Foundation in New York.