The boundaries between districts are, unless otherwise indicated, either the center lines of streets, lanes, watercourses and rights-of-way of power lines, railroads and other public utilities or such lines extended or lines parallel thereto. Where the boundaries of a single district are indicated as including directly opposite sides of a street, lane, lake or watercourse or right-of-way of a power line, railroad or other public utility for any portion of its length, the district so indicated shall be construed to apply to the entire bed of such street, lane, lake or watercourse or right-of-way of such power line, railroad or other public utility lying within such portion of its length. Where uncertainty exists as to the location of any said boundaries as shown on the Zoning Map, the following rules shall apply:

Whenever federal or state-owned property is included in one or more zoning districts, it shall be subject to the provisions of this chapter only insofar as permitted by the Constitution and laws of the United States of America and of the Commonwealth of Pennsylvania.