Are you lost? Many Americans don't realize this, but there is a method to some of our madness. For example if you are on Highway I-5 I would know that you are going either north or south. That is because all odd number highways run north to south. Here are the general rules of thumb.
So if you hear someone talking about Highway 1, and you live in New York, you can make a pretty good guess they are talking about a highway that runs along the west coast.