The Postal Service is shipping all 230,000 carriers new mobile devices with a soon-to-be-activated "panic button."

GPS transmits their location to their supervisors every minute.

Jeff Williamson, chief of human resources for the Postal Service, said the new devices will be rolled out by September, and will cost $200 million.

The new devices also let supervisors warn carriers with alerts, like they did during the recent unrest in Baltimore.

The devices also allow virtually real-time notifications when their package has arrived and more efficient routes to save time and fuel.