In its most basic form, GPS systems provide a vehicle operator with the vehicle’s position in latitude and longitude. A mapping program is usually integrated, which correlates the vehicle’s position with the location of landmarks. Routing programs (similar to the commonly used Internet driving directions) are generally added to give vehicle operators directions to their destination. The central component of a tracking system is a GPS unit with the ability to locate a container, truck, or railcar carrying a food shipment. Tracking systems use GPS data to determine the shipment’s location, then store that information and share it in some manner with the shipping management, and—in case of trouble—can be made available to law enforcement. Basic in-truck GPS tracking systems simply record the location—and perhaps the direction of travel and speed—of the vehicle. The limitation to these systems is that the trailer and its cargo are not directly tracked. If the trailer is separated from the tractor, further information about its location is lost. In these basic GPS tracking systems, location data is downloaded when the truck arrives at its destination. If the trailer is lost, stolen, or abandoned in transit, it cannot be located with this type of system. Trailer tracking systems differ from truck tracking systems in that each trailer or cargo container has its own self-contained, independent GPS tracking unit. Many tracking systems send data with cell phone transmitters that are built into the system. As cell users know, there are still many portions of this country where coverage is lacking, and coverage may be even sparser in Mexico and Central America. When the truck enters one of these unserved areas, no data can be transmitted. Some of the benefits of trailer tracking systems include: (1) Detection of tampering, schedule discrepancies, and unauthorized stops; (2) Increased customer comfort from knowing that their shipment can be located at any time; (3) More precise scheduling of deliveries offers customers the opportunity for savings, efficiencies, and fewer halts in production; and (4) Monitoring breakdowns, equipment failures, operator neglect, and accidents.