Data from the Pennsylvania Department of Education shows an increase in unsolved bomb threats in its public schools over the last three academic years, but a general decrease in terroristic threats.
An Associated Press analysis of school threat data found the disruptions increasing nationwide at the expense of students' learning time and local police departments' resources.
The state department provided data gathered from Pennsylvania's 500 public school districts.
In 2014-15, Pennsylvania schools received 132 unsolved bomb threats by phone, email or other methods. That number is up from 88 in 2013-14 and 82 in 2012-13.
Terroristic threats include solved bomb threats and other threats to commit violence. Pennsylvania schools have recorded more than 500 terroristic threats since the 2009-10 school year.
More than 1.7 million students attend Pennsylvania public schools.