The group wants Congress to take action to pass legislation to require background checks for all sales, to limit military-style assault weapons and high-capacity magazines and to make gun trafficking a federal crime.
The ad features 30 mayors, including Bloomberg, Boston Mayor Thomas Menino and Philadelphia Mayor Michael Nutter.
States with the most gun control laws have a 42 percent lower gun death rate than states with the least number of gun control laws, according to a 50-state study released Wednesday that suggests sheer quantity of measures might make a difference. Read more about that study here.
On the web: www.DemandAction.org/Mayors.