The Governing Body of the City may, from time to time, in the manner
hereinafter set forth, amend the regulations imposed in the Districts
created by this chapter, amend District boundary lines, provided that
in all amendatory orders adopted under the authority of this section,
due allowance shall be made for existing conditions, the conservation
of property values, the direction of building development to the best
advantage of the entire City, and the uses to which property is devoted
at the time of such amendatory order. In case, however, of a protest
against such change duly signed and acknowledged by the owners of
30% or more, either of the areas of the land (exclusive of streets
and alleys) included in such proposed change or within an area determined
by lines drawn parallel to and 185 feet distant from the boundaries
of the District proposed to be changed, such amendment shall not become
effective except by the favorable vote of 2/3 of all the members of
the Board of Aldermen.