The main battery gun turrets had 18-inch (457 mm) thick faces and were mounted atop barbettes 17.3 inches (440 mm) thick. The conning tower had 16-inch (406 mm) thick sides.

To withstand an onslaught from rival battleships, the North Carolina was outfitted with armor measuring 16 inches thick along the gun turret and 12 inches thick along the belt.