Are you kidding me ?  While of course the law forbids free speech on public land , who ever put those there was just some over energized Trump supporter---not some person making a statement on law and order.  At most busy intersections we see signs from all those running that by law shouldn't be there.  Maybe , just maybe , someone figures if Hillary Clinton can blatantly break the law while putting our nation at risk with the blessing of the FBI and Obama state department---placing signs where they shouldn't be is small taters , so what the heck.   No need to worry though . Before days end some liberal will tear them all down----just as they do with Don Young signs each and every election.