I thought it was once stated by AAA that food and gas establishments would only be shown at each exit IF the place is 24 hours AND no further than 1 mile off the exit. Yet, in White Plains, NY (as one of many examples) I went on a wild goosechase because of those bloody signs! What gives here? Are the Feds now taking bids for placing logos on these blue highway signs? - Jinx :mad:
The actual rules can be modified by the states. Different states specify “open 16 hours (or 12 hours), 7 days a week,” others state that gas must be open 24/7 within one mile, but food may be close at 11:00 p.m. and be within three miles. I’ve seen several different applications. Iowa, for example, allows a sign for a service up to fifteen miles away if no service is closer.
I believe there is a stipulation that for restaurants, if there are more than 3 or 6 (depending on the size of the sign) near the exit, first dibs go to the ones that serve breakfast, lunch and dinner. IIRC, there was a fight a while back between like Burger King and KFC near one of the exits. The KFC got on the sign, the BK didn’t. BK said that they should be on there since the KFC only served breakfast to its employees, and not to the general public… I don’t recall how it ended though… (it was a while back)
Heck… if there is a serivce within 2-3 miles (and without 97 turns), I am generally happy.
(Doing some more research)
according to the Feds
There is a lot of discussion on when to put distances on the signs, visibility from the road, etc., but I would just recommend you read the wonderful publication for your transportation enjoyment. 
I always assumed that the place had to pay the state to have their sign posted.