discussed Cited "see, e.g." National Advertising Company v. City of Raleigh, North Carolina, Southern Environmental Law Center, Amicus Curiae See, e.g., Art Neon Co. v. City and County of Denver, 488 F.2d 118, 122 (10th Cir.1973) (upholding five-year amortization period for outdoor signs as reasonable prior to period's expiration), cert. denied, 417 U.S. 932 , 94 S.Ct. 2644 , 41 L.Ed.2d 236 (1974); see also Summey Outdoor Advertising, Inc. v. The County of Henderson, 96 N.C.App. 533 , 386 S.E.2d 439, 446 (1989) (same), pet. for disc. rev. denied, 326 N.C. 486 , 392 S.E.2d 101 (1990); R.O.