This Gun Control Billboard Counts How Many Americans Have Been Killed Since Sandy Hook

A pro-gun control billboard on the Massachusetts Turnpike has been updated to count how many Americans have died from gun violence since the shootings at Sandy Hook Elementary School a year ago.

The billboard, from the nonprofit group Stop Handgun Violence, estimates that more than 32,000 Americans have died in gun-related incidents in the year since Adam Lanza killed 20 children and 6 adults with a semiautomatic rifle at an elementary school in Newtown, Conn.

A reporter at Boston's PBS and NPR station posted a photo of the billboard on Twitter. It reads: "Assault Weapons Have Stopping Power. Fortunately, So Does Your Vote. We Need A Federal Assault Weapons Ban NOW!"

Stop Handgun Violence has had its 250-by-20 foot billboard in the shadows of Boston's Fenway Park since 1995. Starting in 2011, the billboard showed the number of U.S. gun deaths since the 2010 elections, with the billboard later being updated to include 20 handprints for each of the children murdered at Sandy Hook.

Stop Handgun Violence calculated the number of deaths since Sandy Hook using the Centers for Disease Control's data on the average number of firearm deaths over a 30-year period.

Stop Handgun Violence and other advocates for increased firearms restrictions were frustrated this past April, when proposed laws to increase background checks and ban assault weapons were rejected by the U.S. Senate four months after the Sandy Hook shootings.