This law holds in Alaska, Hawaii, Maine, and Vermont. 3 out of the 4 are outermost states of the U.S., and the other is close to being so. Perhaps since there i

This law holds in Alaska, Hawaii, Maine, and Vermont. 3 out of the 4 are outermost states of the U.S., and the other is close to being so. Perhaps since there isn't much interstate traffic going through these states and their state populations are low, there was not so great of an incentive for advertisers to lobby against such laws banning highway ads.