L4D2 route
So my brother and I were talking zombies which lead to l4d2. I had questions about the route and looked at the wiki. It says they took the car to the carnival in griffin county, GA. But there is no griffin county. I thought maybe they meant griffin the city, but it's not off I-16, I-16 turns into a different highway in Macon. Am I totally off base here? Can anyone help mee make sense of the route?