The location and boundaries of such districts are hereby established as delineated and shown on the revised Zoning Map accompanying this chapter and forming a part thereof, upon which the various use districts or zones are designated by the symbols shown on said map. Where a use district is shown as a strip of land along a road or highway, the depth of such district, unless otherwise shown on the Zoning Map, shall be 200 feet from the side line of the road or highway upon which such property fronts.