opinion: Mr. Justice Douglas
  delivered the opinion of the Court.
  There was a cement plant in Merced County, California, which was sold to petitioner — a corporation of Colombia — for export to South America. An export license was obtained and a letter of credit in favor of the seller deposited here. Title passed' and possession was taken for the purchaser. A company, which was a common carrier, was employed to do the dismantling and packaging for shipment. As the dismantling proceeded, shipments were labeled with appellant’s name as consignee and delivered to a rail carrier.
  Respondent, acting under a California statute, levied a personal property tax on the property for the tax year 1945-1946. The tax date was March 5, 1945. On that date 12 per cent of the plant had been shipped out of the county. That portion was relieved of the tax. The balance was taxed. That included the 10 per cent which had been dismantled and crated or prepared for shipment, 34 per cent which had been dismantled but not crated or prepared for shipment, and 44 per cent which had not -been dismantled. But before the end of January, 1946, all the property had been shipped by rail to a port and was en route to South America by ocean carriér.
  . Article I, § 10, Cl. 2 of the Constitution provides in part that, “No State shall, without the Consent of the Congress, lay any Imposts or Duties on Imports or Exports, except what may be absolutely necessary .for executing it’s inspection Laws . . . .” Appellant claimed that this tax was laid on an export and was therefore unconstitutional. It paid the tax under protest and brought this suit to recover it. The trial court, holding that the entire plant was an export on the tax assessment day, granted judgment for appellant. The Supreme Courvt of California reversed. 32 Cal. 2d 68, 194 P. 2d •527. The case is here on appeal. 28 U. S. C. § 1257 (2).
  “. . \ goods do not cease tó be part of the general mass of property in the State, subject, as such, to its jurisdiction, and to taxation in the usual way, until they have been shipped, or entered with a common carrier for transportation to another State, or have been started upon such transportation in a continuous route or journey.” Coe v. Errol, 116 U. S. 517, 527. That test was fashioned to determine the validity under the Commerce Clause of a nondiscriminatory state tax. But as we noted in Richfield Oil Corp. v. State Board, 329 U. S. 69, 79, it is. equally applicable to cases arising either under Art. I, § 10, Cl. 2 (the Import-Export Clause) or under Art. I, § 9, Cl. 5, which prohibits Congress, from laying any tax on “Articles .exported from any State.”
  Under that test it is not enough that there is an intent to export, or a plan which contemplates exportation, or an integrated series of events which will end with it. See Turpin v. Burgess, 117 U. S. 504; Cornell v. Coyne, 192 U. S. 418. The' tax immunity runs to the process of. Exportation and the transactions and documents embraced in it. Fairbank v. United States, 181 U. S. 283; United States v. Huoslef, 237 U. S. 1; Thames & Mersey Ins. Co. v. United States, 237 U. S. 19. Delivery of packages to an exporting carrier for shipment abroad (Spalding & Bros. v. Edwards, 262 U. S. 66) and the delivery of oil into the hold of the .ship furnished by the foreign purchaser to carry the oil abroad (Richfield Oil Corp. v. State Board, supra) have been held sufficient. It is the entrance of. the articles into the export stream that marks the start of the process of exportation. Then there is certainty that the goods are headed for their foreign destination and will not be diverted to domestic use. Nothing less will suffice.
  So in this case it is not enough that on the tax date there was a purpose and plan to export this property. Nor is it sufficient that in due course that plan was fully executed. Part of the plant that is taxed was dismantled, but it had not been delivered to any carrier for export or otherwise started on its journey on the tax date. It might still have been diverted into the domestic market. The fact that any such diversion would entail a breach of contract, that a part of the plant had already started on its export journey, that an export license had been obtained and a letter of Credit deposited in this country increases the expectation on the tax daté that exportation of the entire plant would eventuate. But that prospect, no matter how bright, does not start the process of exportation. On the tax date the movement to foreign shores had neither started nor been committed.
  Some reliance is apparently placed on the fact that the dismantler was a licensed carrier for interstate and foreign commerce and that its employment included the loading of the property on railroad cars for shipment to the seaboard. But the dismantler had not in this case started the movement of the property to the rail carrier. Hence we need not determine whether that intermediate transportation would be part of the export process.
  Affirmed.
  Rev. and Tax. Code (Deering, 1939), Div. I, §§103, 106, 201, 202 (e), 405.
  The meaning of “export” is the same under the two Clauses. See Richfield Oil Corp. v. State Board, 329 U. S. 69, 83 and cases cited.