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