First of all, let me assure you, that OC'ing is not enough for a charge of going armed to the terror of the public. Let me also assure you, that very few people actually understand what that charge means (unfortunately, too many LEO fall into this category).
OC'ing is legal in NC under the common-law presumption that anything not specifically named illegal by law, is legal. (While this is true, it is problematic, as there is no statute to cite to convince the unwashed).
A charge of going armed to the terror of the public (ironically, the charge itself is a common-law crime, as there is no statute specifically banning), has four elements:
1) Going armed with a dangerous and unusual weapon (yes firearms count as both, State v. Robert S., Huntley, 1843)
2) For the purpose of terrifying others
3) goes about on public highways
4) In a manner to cause terror to others
Huntley also makes it clear that simply carrying an unconcealed weapon IS NOT enough to merit a charge of going armed to the terror of the public.
Now, the difficult part: There is a law in NC that allows cities and counties to "regulate" the "display" of firearms on the streets, sidewalks, alleys, or other public property.
Some cities has passed ordinances outright banning OC in their city limits - it is generally believed that such outright bans are unconstitutional - but many of these ordinances are still on the books. Many people will say they have OC'd with no problems in Cary, which has this type of ordinance, but YMMV.
Other cities, such as Chapel Hill, have passed ordinances banning the OC of weapons that are smaller than a certain size. These types of ordinances are not CLEARLY unconstitutional, and anyway carrying in those towns should be VERY careful to ensure they know whether they are in compliance with the law, or have made a conscious decision to challenge such ordinance.
I offer no opinion on whether to obey or challenge, but I believe that should be a conscious choice, not the result of ignorance (which we all know is not defense before the bar of justice)
AFAIK, there are no such ordinances in Western NC, but Asheville does ban firearms from its parks.