The Global Positioning System (GPS) was developed by the U.S. Department of Defense. The only system of its kind in the world, GPS uses the transmission of microwave signals from a network of 24 satellites orbiting 12,000 miles above Earth to pinpoint a receiver's location, as well as its speed and direction of travel.
Initially restricted to the military, President Reagan authorized the civilian use of GPS in 1983 after 269 passengers and crew died on a Korean airliner that was shot down when it strayed off course into Russian airspace. GPS quickly became a widely used navigation aid throughout the world. Compared to their early predecessors, today's GPS devices are quite compact and extremely accurate. Thanks to these advances, many motorists now rely on GPS car navigation systems to avoid getting lost.
GPS car navigation systems can be factory-installed on new autos or purchased as an add-on accessory. Combining the use of signals from the satellites with interactive on-board maps, GPS car navigation systems can plot routes of travel to a given destination based on a number of variables. Some GPS car navigation systems are interconnected with sources of traffic information, enabling them to automatically account for construction and congestion when determining the best route. If a driver misses a turn, GPS car navigation systems can quickly correct for the error with an updated routing. Providing voice or visual instructions, these units also can help drivers find the nearest gas station or their favorite restaurant.