I have always disliked “back-seat drivers” because they never cease to state the obvious. I figure if someone eight inches away from me can see something I can’t, we’re already in big trouble. But those prejudices have to change fast as there’s a new back-seat driver in my family that won’t flinch at the threat of being dumped off at a street corner – the global positioning system, or GPS, unit. Developed by the U.S. Department of Defense in the 1970s, GPS devices can pinpoint a person’s location to within several meters by using a network of more than 24 satellites that orbit approximately 11,000 miles above Earth. That’s why these hard-plastic electronic gadgets are the newest must-have among outdoors enthusiasts and the directionally challenged. Can’t figure out which way is north or south? No problem. If you’re like my sister, who gets lost in Wal-Mart, a GPS unit is your new best friend. Type in an address and it’ll give you step-by-step directions as you’re driving. An arrow on the screen will show exactly where you are and there’s a virtual speedometer. But there can be problems. One time I was driving with a friend in Los Angeles inching down the 105 Freeway. She had a portable GPS unit on the dashboard, which interrupted our conversation with a command to “Take exit in 300 meters.” It didn’t know we were in the car-pool lane. In December, a British ambulance crew transferring a patient to a London-area hospital relied on their GPS – and drove 200 miles in the wrong direction. As with all technology that becomes available to America’s pencil pushers, GPS units are popping up in people’s hands and vehicles as stores slash price tags. The NPD Group, a market research firm in New York, has reported that the average price of a GPS unit fell by more than 50 percent in the past year – from $684 in 2005 to $322 in 2006 – helping to fuel a shopping frenzy that saw sales increase by 670 percent. With numbers like that, marketers are salivating. Dunkin’ Brands was the first to litter the digital roadway by signing an agreement with GPS manufacturer TomTom. Through this collaboration, users now can pinpoint every Dunkin’ Donuts and Baskin Robbins in the country. The GPS unit will beep or flash an icon as you drive by a franchise. Before T.S. Elliot died in 1965, an age eerily devoid of laptops, cell phones and iPods, the famed poet lamented, “Where is all the knowledge we lost with information?” Mr. Elliot, we still can’t answer that question. Chantal Allan is an avid driver and a graduate journalism student at the University of Southern California.160Want local news?Sign up for the Localist and stay informed Something went wrong. Please try again.subscribeCongratulations! You’re all set!