In the 10 years since the 9/11 attacks, schools and universities have carried out many steps to make facilities safer for students and staff members. Many of the improvements can be attributed to greater awareness of the need for security as well as the availability of new and improved tools to enhance campus safety.

"Indicators of School Crime: 2010," compiled by the National Center for Education Statistics and the Bureau of Justice Statistics, provides numerical evidence of those security upgrades. The percentage of public school buildings that locked or monitored doors during school hours increased from 74.6 percent in 1999-2000 to 89.5 percent in 2007-08.

The statistics also show that schools have become more cognizant that the presence of unauthorized visitors in a school is a potential security problem. In 1999-2000, 25.4 percent of public schools required faculty and staff to wear badges or photo identification; in 2007-08, the figure more than doubled, to 58.3 percent. Schools that required students to wear badges or IDs also jumped significantly, from 3.9 percent in 1999-2000 to 7.6 percent in 2007-08.

Public schools also have taken advantage of the greater affordability and availability of technology to bolster campus safety. In 1999-2000, 19.4 percent of schools used video cameras to monitor activity; by 2007-08, security cameras were being used by 55 percent of public schools. More than 73 percent of public schools reported in 2007-08 that two-way radios were part of their security efforts; in 1999-2000, researchers didn’t compile that data. Also in 1999-2000, before the proliferation of text messaging and social media, federal researchers didn’t gather data about schools’ use of electronic notification systems for emergencies. In 2007-08, 43.2 percent of public schools said they had such a system to disseminate information about school emergencies.

Even more mundane security enhancements, such as classroom telephones, became a more common element of school security in the 2000s. In 2007-08, 71.6 percent of schools provided phones in most classrooms; in 1999-2000, only 44.6 percent of schools did.