Clause 5. No Tax or Duty shall be laid on Articles exported from any
State.

TAXES ON EXPORTS

This prohibition applies only to the imposition of duties on goods by
reason of exportation.[1517] The word "export" signifies goods exported
to a foreign country, not to an unincorporated territory of the United
States.[1518] A general tax laid on all property alike, including that
intended for export, is not within the prohibition, if it is not levied
on goods in course of exportation nor because of their intended
exportation.[1519] Where the sale to a commission merchant for a foreign
consignee was consummated by delivery of the goods to an exporting
carrier, the sale was held to be a step in the exportation and hence
exempt from a general tax on sales of such commodity.[1520] The giving
of a bond for exportation of distilled liquor is not the commencement of
exportation so as to exempt from an excise tax spirits which were not
exported pursuant to such bond.[1521] A tax on the income of a
corporation derived from its export trade is not a tax on "articles
exported" within the meaning of the Constitution.[1522]

Stamp Taxes

A stamp tax imposed on foreign bills of lading,[1523] charter
parties,[1524] or marine insurance policies,[1525] is in effect a tax or
duty upon exports, and so void; but an act requiring the stamping of all
packages of tobacco intended for export in order to prevent fraud was
held not to be forbidden as a tax on exports.[1526]

Clause 6. No Preference shall be given by any Regulation of Commerce or
Revenue to the Ports of one State over those of another: nor shall
Vessels bound to, or from, one State, be obliged to enter, clear, or pay
duties in another.

THE "NO PREFERENCE" CLAUSE

The limitations imposed by this section were designed to prevent
preferences as between ports on account of their location in different
States. They do not forbid such discriminations as between individual
ports. Acting under the commerce clause, Congress may do many things
which benefit particular ports and which incidentally result to the
disadvantage of other ports in the same or neighboring States. It may
establish ports of entry, erect and operate lighthouses, improve rivers
and harbors, and provide structures for the convenient and economical
handling of traffic.[1527] A rate order of the Interstate Commerce
Commission which allowed an additional charge to be made for ferrying
traffic across the M