Why dont billboard company's put billboards on freeway over passes as opposed to along side the road?

Question

I see billboards all the time along side the road, but yet freeway over passes are left blank other than when they put the mileage to city's... Is there a reason?

Answer 1

It's against the law for what should be an obvious reason: You don't want to distract drivers with unnecessary signs clumped together with traffic signs.

Answer 2

It is probably not legal for them to do that.  Probably a state/federal requirement.

Answer 3

In most places they have to be put on private property not on highway right of way or overpasses.

Answer 4

It would be one very big distraction to the drivers and we dont need that along with liability that these companies would be facing because the drivers would say that they had their accident because they were reading the billboard sign.....