To safeguard against abductions and molestations, one school in New Mexico is using a security system that scans the palm of a parent's hand so that no unauthorised adult can leave with any child.
Officials argue such technology is needed to ensure the safety of students and teachers in public school buildings.
In Trenton, New Jersey, the school district reports that surveillance cameras have cut down on violent incidents in the high school, which also has security guards and metal detectors to watch over its 3,000 students.
An elementary school in Albuquerque, New Mexico, has just started using a high-tech system to ensure that children can't be taken away by abductors - including divorced parents who do not have custody.
The "hand geometry identification device," initially developed for use by the military, colleges, prisons, banks and airlines, was installed by a government defence laboratory at an elementary school for a two-year trial period.
The scanner uses infrared light to instantly capture a digital image of a parent or guardian's right hand. The image is stored in case administrators need to cross-check the identity of an adult who asks to take the child out of school.