The Columbine shooting of April 20, 1999, is still considered one of the worst tragedies in the modern American history. This tragedy took 13 lives and it seems to have forever changed the way the American society thinks about school safety, security and gun control. Still, considering an extremely high number of shootings that occurred in schools in the USA after 1999, it seems that the problem is not even close to a solution.

In 1999, after the Columbine massacre in April, there were three other school shootings in the USA, in Georgia (six students injured), California (two fatalities) and in New Mexico (one fatality). In February 2000, another tragedy shook the nation after a six-year old boy shot and killed his classmate in Flint, Michigan. In the following years, the nation saw two to three school shootings per year. The 2005 Minnesota school shooting involved none fatalities and in 2006 five girls were killed and five others injured in a shooting in an Amish school in Pennsylvania.

The deadliest school shooting by a single gunman in the history of the United States remains the Virginia Tech massacre of 2007. On April 16 Seung-Hui Cho, who was a senior at Virginia Tech, conducted two separate attacks that lasted over two hours. He shot and killed 32 people and wounded 17 before committing suicide. This shooting was the second-deadliest mass murder since the Bath School disaster of 1927 (44 victims) and it even surpassed the Columbine massacre of 1999.

Much like the Columbine shooting, the Virginia Tech massacre sparked a nationwide debate over issues involving gun control, the culture of violence and obvious problems in the American system regarding mental issues. Still, just a year later, five people were killed and 21 were injured in a shooting at the Northern Illinois University. Two students were killed in Littleton, Colorado in February 2010, three died in Chardon, Ohio in February 2012 and seven died in Oakland, California, in April 2012. Overall, there were over 40 school and campus shootings between Columbine in 1999 and 2013.

On February 14, 2012, the Sandy Hook Elementary School in Newtown, Connecticut, was the scene of the second-deadliest school shooting in the USA history (behind Virginia Tech massacre). The shooter, the 20-year old Adam Lanza, brought a shotgun to the elementary school, shot and killed 20 children and six adults and committed suicide. The nation was deeply shaken and new debates ensued. The entire world was puzzled over how much violence there is in American schools and how young the shooters and their victims usually are. Considering the extremely high number of school shootings in the USA, it is clear that this is probably the most urgent problem the nation is facing at this moment, while Columbine, Virginia Tech and Sandy Hook remain as deeply disturbing warning signs.