New State Law, effective October of 2011, actually protects those trashy campaign signs within a highway right-of-way (aka within 3 feet of the pavement), so it is actually a misdemeanor to remove a lawfully placed sign. However, they are only protected 30 days before early voting starts and must be removed within 10 days of the election. Anything outside that window is simple litter and is fair game. There are some other little guidelines for the signs but they are reliant on the NCDOT to enforce them, which they won't because they have neither the manpower nor the interest. The most important condition is that the adjacent property owner must consent to their placement in the ROW in front of their property.
So all the cities and towns that had rules to prevent this kind of clutter are now scratching their heads since the State law trumps the local ordinances. So get ready, this year will be a bumper crop for political garbage, in more ways than one.