Maryland Transportation Section 8-736
§ 8-736.
  (a)   The political subdivisions of this State have full authority, under their respective zoning powers:
    (1)   To zone areas for commercial or industrial purposes; and
    (2)   In these areas, to govern the size, spacing, and lighting of outdoor signs.
  (b)   Notwithstanding any provision of this part or any rule or regulation of the Administration:
    (1)   Local zoning regulations that relate to outdoor signs in commercial or industrial areas shall govern within the zoned area; and
    (2)   If a political subdivision adopts comprehensive zoning that includes the regulation of outdoor signs:
      (i)   The Administration may so certify to the Federal Highway Administrator; and
      (ii)   On certification, the control of outdoor signs in commercial or industrial areas transfers to the political subdivision.