Del. Code tit. 22 § 704
Each incorporated city or town established under this title may, by action of its city council or town commissioners, adopt an official map prepared under the direction of such planning commission and showing the public ways and parks therein as theretofore laid out and established by law and the private ways then existing and used in common by more than 2 owners. Such official map is hereby declared to be established to conserve and promote the public health, safety and general welfare. Upon the adoption of such a map and upon any change therein or addition thereto made, as hereinafter provided, the city or town clerk shall forthwith file with the recorder of deeds in the respective counties a certificate of such action and a copy of such map as adopted or as changed or added to.
22 Del. C. § 704