— The states are prohibited from levying any impost or duty upon imports or exports. U.S. Const, art. 1, § 10.
Our business and occupation tax law accommodates this restraint by excluding from that tax amounts derived from business which the State is prohibited from taxing under the United States Constitution. RCW 82.04.430 (6).
Here we are concerned with the correctness of the trial court’s holding that plaintiff’s sales, as described later, involved exports and therefore were free from the state business and occupation tax on retailing as imposed by RCW 82.04.250. Plaintiff seeks a refund, pursuant to RCW 82.32.180, of the tax assessment made by the State.
Before considering the facts, we shall set out the principles which necessarily guide us in determining whether this tax does what the constitution prohibits.
At the outset we note the case is somewhat unique in that the United States Government itself is the purchaser. While most export cases involve a foreign purchaser, there is no authority that such is an implied requirement of the constitutional provision. Indeed it has been held that the United States, as a buyer for export, is entitled to the benefit of the prohibition against taxes on exports. Union Oil Co. v. Los Angeles, 227 Cal. App. 2d 608, 38 Cal. Rptr. 923 (1964).
To enjoy the constitutional protection as an export, goods must have entered the export stream with certainty of a foreign destination. Neither intent to export nor the ultimate fact of actual exportation alone is sufficient to invoke the immunity. Richfield Oil Corp. v. State Bd. of Equalization, 329 U.S. 69, 91 L. Ed. 80, 67 S. Ct. 156 (1946); Empresa Siderurgica, S.A. v. County of Merced, 337 U.S. 154, 93 L. Ed. 1276, 69 S. Ct. 995 (1949).
It must be recognized that the prohibition is absolute except for the very narrow exception of allowing the impo*446sition of inspection fees. Richfield Oil Corp. v. State Bd. of Equalization, supra.
The United States Supreme Court cases mandate that exports be given liberal protection. A.G. Spalding & Bros. v. Edwards, 262 U.S. 66, 67 L. Ed. 865, 43 S. Ct. 485 (1923), so states; and Thames & Mersey Marine Ins. Co. v. United States, 237 U.S. 19, 59 L. Ed. 821, 35 S. Ct. 496 (1915), illustrates application of a liberal approach by holding that the protective umbrella is great enough to prohibit a stamp tax on insurance policies insuring the exported goods.
Entry into the export stream must be the start of a continuity of movement. Carson Petroleum Co. v. Vial, 279 U.S. 95, 73 L. Ed. 626, 49 S. Ct. 292 (1929). Yet the journey may be interrupted if the purpose of the interruption is “reasonable and in furtherance of the intended transportation.” Hughes Bros. Timber Co. v. Minnesota, 272 U.S. 469, 476, 71 L. Ed. 359, 47 S. Ct. 170 (1926). The point has been otherwise stated as allowing interruption to “promote the safe or convenient transit” of the goods. Champlain Realty Co. v. Brattleboro, 260 U.S. 366, 376, 67 L. Ed. 309, 43 S. Ct. 146, 25 A.L.R. 1195 (1922). In application the following situations have been deemed to be permissible interruptions: (1) holding of logs in a boom in a river to await subsidence of high water, Champlain Realty Co. v. Brattleboro, supra; (2) shipment to an independent export packer for preparation for ocean travel, Gough Indus., Inc. v. State Bd. of Equalization, 51 Cal. 2d 746, 336 P.2d 161, cert. denied, 359 U.S. 1011, 3 L. Ed. 2d 1037, 79 S. Ct. 1151 (1959); (3) accumulation and storage for convenient and efficient loading of ships. Cargill of Cal., Inc. v. County of Yolo, 26 Cal. App. 3d 704, 103 Cal. Rptr. 257 (1972); Carson Petroleum Co. v. Vial, supra. Some of these cited cases involved the commerce clause, but the rationale is pertinent here.
It was contended in a number of these cases, as does the State here, that the owner of the goods might divert them from the export stream since they are not irrevocably bound overseas until they are on board the *447ship. In A.G. Spalding & Bros. v. Edwards, supra, a New York company purchased goods for a foreign company. A tax on the manufacturer of the goods was struck down and Mr. Justice Holmes stated at page 69:
The fact that further acts were to be done before the goods would get to sea does not matter so long as they were only the regular steps to the contemplated result. . . . Neither does it matter that the title was in [the foreign buyer’s agent] and that theoretically they might change their mind and retain the bats and balls for their own use. . . . Theoretical possibilities may be left out of account.
Hughes Bros. Timber Co. v. Minnesota, supra, was a commerce clause case, but the court said at page 475:
The character of the shipment in such a case [when the owner retains control of the transportation and can divert] depends upon all the evidential circumstances looking to what the owner has done in the preparation for the journey and in carrying it out. The mere power of the owner to divert the shipment already started does not take it out of interstate commerce, if the other facts show that the journey has already begun in good faith and temporary interruption of the passage is reasonable and in furtherance of the intended transportation . . .
Turning to the facts, we find that the plaintiff was the successful bidder to supply parts and equipment of a specified make to the General Services Administration of the United States (GSA). From the invitation to bid to the accomplished fact, all such items were destined for and delivered to military installations in Southeast Asia, Korea and Japan. All sales in the relevant period of 1967-71 were pursuant to individual GSA purchase orders, each of which identified a particular part, a named overseas recipient and a specific overseas destination. Pursuant to the purchase order requirements, the shipments were trucked from Seattle to GSA’s Tacoma packing facility. The Tacoma facility had been established for the sole purpose of packing items for overseas shipment to United States military establishments. On the average, materials were at the packing oper*448ation for only 7 or 8 days before being loaded on a ship or airlifted out. During that time they were inspected for compliance with specifications and packaged for overseas shipment.
From these facts, the court concluded that when the items were loaded on the trucks in Seattle it was certain that they were destined for export, that they then entered the export stream and that the packing in Tacoma was not •a break in the stream of export, but in furtherance of it. We agree. The bid itself specified that the goods were for export. The purchase orders identified the recipient overseas agency and the foreign destination. The delivery, without exception, was to a facility designed solely to package the goods for overseas shipment. Under these facts it is conclusive that there was a meshing of the certainty of export with the commitment to and actual commencement of transportation in the export stream. There was no diversion and the possibility of diversion was merely hypothetical and remote. Realities and probabilities are controlling, not theoretical possibilities.
The State relies on our decision in Eardley Fisheries Co. v. Seattle, 50 Wn.2d 566, 314 P.2d 393 (1957). That case enunciates principles in accord with our decision here, but the facts distinguish it. The goods in Eardley were frozen seafood held by the purchaser in cold storage depots for periods as long as 120 days after the government accepted delivery. Domestic use was obvious and found to exist. The tax accrued upon delivery to the local storage. The court correctly held that at the time of sale, delivery to the storage, there was no certainty of export of identifiable goods nor entry at that point into the export stream.
Finally the State’s own administrative rule, WAC 458-20-193C(3) acknowledges that something short of delivery at dockside will constitute entry into the export stream. It states that it is sufficient if there is delivery to “other vehicles of transportation under circumstances where it is clear the goods will be taken to a foreign destination.” *449Those are the circumstances here; it is clear and the trial court was correct.
The judgment is affirmed.
Finley, Stafford, Wright, and Utter, JJ., concur.