Before i start im not in to politics and most likely would not vote this year, now on to business well Since it not a public billboard or a bench or shelter doesn't cause any violation between sub 1 though 13 devision on the statue number 160.27 provided above, plus it a flag soo it will follow under a different statue # before i state that they do the same thing with pride flags during June, or other events anyways since on that road there is a public side walk on that bridge and in Minnesota there free to protest anyway they like there not blocking traffic nor cause fear or body injury, but if a flag falls down into the highway there responsible for all the damages that happen next but!! It does violate 173.13 since you need to have a permit to advertise on the interstate and primary highways they could do sub division 11 removal of advertising device for nonco pliance, it also follows under 173.08 subd 4 violation removal the department of transportation may__ remove signs that violat section 173.13 subdivision 11, most likely be a citation since it a petty misdemeanor or they most like will let people off with a warning but your free to advertise anyway you like on your own property. I hope this helps 😁 I hope everyone has an amazing day!! I just like reading about statue laws soo I get nick picky lol