LOL. It doesn't get to the level of whether people can hang signs on overpasses. This is getting just ridiculous.It is a part of the interstate highway system Damo. States must agree to the terms under the federal highway system. There could be a few exceptions here and there, but generally a basic set of rules associated with interstate highways exist. Limited access, No horses, signage rules, etc...
Not all the laws across the land are uniform, yet. I know the Dems are working toward that, but they just aren't, even in this.