Twenty-three mass shootings have occurred in the US in the year since the Sandy Hook school massacre in Newtown, Connecticut, leaving more than 100 dead across 17 states.

Today marks the anniversary of the Newtown shooting, in which Adam Lanza killed 20 children and six teachers at Sandy Hook Elementary School. Lanza, who also killed his mother before leaving home for the school, reportedly had an obsession with mass murders, especially the 1999 Columbine High School massacre in Colorado, in which 13 people died excluding the two perpetrators.

While there is no official definition for a mass shooting in US law, the FBI defines a mass murder as the killing of four or more people without an extended period of “cooling-off” by the perpetrator. This interactive applies that FBI definition but restricted to gun violence.

These parameters mean that some high-profile incidents in 2013 don’t classify, including the incident at LAX airport on 1 November in which one person was killed and three more were injured.

The state with the highest number of mass shootings and deaths in the past year was Texas, with a total of 17 people dying in four separate incidents, excluding the perpetrators. The second highest number was in Oklahoma, where 12 people died in three separate incidents.The highest individual death toll occurred in Washington D.C., where 12 people died in the Navy Yard shootings in September, again excluding the shooter.
Florida also had several mass shootings since Newtown: a killing spree in Hialeah, in which six people died excluding the shooter, and a shooting in Jacksonville in which four people were found shot inside a house.
In the wake of the Sandy Hook massacre, President Barack Obama has urged community members and Congress to take “common sense” steps towards ending gun violence.
The Brady Campaign to Prevent Gun Violence and the Law Center to Prevent Gun Violence jointly issued a 2013 scorecard that ranks state gun legislation in all fifty states. The scorecard ranks each state along thirty-eight criteria that address a variety of policy areas, including allowance of firearms in public places, and background checks and access to firearms.
Texas and Oklahoma were ranked 33 and 35, respectively, out of the fifty states, and are assigned a grade of “F”. The worst-rated state was Arizona, the best California.

via Interactive graphic: the 23 US mass-shootings since Sandy Hook – Telegraph.