The mayor of Chicago has unveiled a series of new measures aimed at making it harder to buy firearms in one the nation’s deadliest cities for gun violence. The proposal from Rahm Emanuel calls for videotaping all gun sales and limiting them to one per month. Retailers would be required to undergo background checks, complete training, and face quarterly audits of their inventory. Gun buyers would also face a waiting period of up to 72 hours. A city report blames lax gun laws in neighboring states for the spread of firearms in Chicago. Sixty percent of guns used to commit crimes were originally purchased out of state.