They're staples of each trek down every open highway in the country: the interstate exit business signs. The ones that point you to the nearest gas station or restaurant. But how do they work? Which businesses are chosen? How much do they cost? And how often do they change? In Kentucky, the state has handed off the operation of the sign program to a private company, Kentucky Logos, and receives a portion of the sales. The company, which has handled the program since 1997, is a subsidiary of Interstate Logos, which handles similar programs in 22 of the 28 states that have privatized the service.