N.H. Rev. Stat. Ann. § 44:4-a

All boundaries of wards, other than those boundaries which are coterminous with the boundaries of municipalities, shall follow easily identifiable physical features. For the purposes of this section, physical features include public and private ways, public utility lines, railroad tracks, and surface waters. Ward lines shall be clearly shown on a map of suitable scale. Those portions of physical features with names and used as ward boundaries shall be clearly labeled on the ward map.