increase the pressure of natural gas and thereby permit it to be transported to purchasers in other States.[547] Similarly, a tax so much per pound on shrimp taken within the three-mile belt of the coast of the taxing State was valid, since the taxable event, the taking of the shrimp, occurred before they could be said to have entered the interstate commerce stream.[548] PRODUCTION FOR AN ESTABLISHED MARKET But while the production of goods intended for the interstate market is taxable by the State where it takes place, their purchase for an established market in another State is interstate commerce and as such is neither regulatable nor taxable by the State of origin, provided at any rate their trans-shipment is not unduly delayed.[549] Thus, oil gathered into the pipe lines of a distributing company and intended for the most part for customers outside the State, is in interstate commerce from the moment it leaves the wells;[550] and a like result has been reached as to natural gas.[551] "The typical and actual course of events," says the Court, "marks the carriage of the greater part as commerce among the States and theoretical possibilities may be left out of account."[552] REJECTION OF THE ORIGINAL PACKAGE CONCEPT IN INTERSTATE COMMERCE But the question also arises as to when goods entering a State from another State become part of the mass of property of the former and hence taxable by it? In Brown _v._ Maryland,[553] Chief Justice Marshall, had remarked at the close of his opinion, "We suppose the principles laid down in this case, apply equally to importations from a sister State."[554] Forty-two years later, in Woodruff _v._ Parham,[555] an effort was made to induce the Court, in reliance on this dictum, to apply the original package doctrine against a Mobile, Alabama tax on sales at auction, so far as it reached "imports" from sister States. The Court refused the invitation; first on the ground that Marshall's statement was _obiter_, the point not having been involved in Brown _v._ Maryland; second, because usage contemporary with the Constitution and of the Constitution itself confined the term "imports" as employed in article I, section 10 to imports from abroad; third, because the tax in question was nondiscriminatory. At the same time, nevertheless, reference was made to the power of Congress to interpose at any time in exercise of its power over commerce, "in such a manner as to prevent the States from any oppressive interference with the free interchange of commodities by the citizens of one State with those of another."[556] The same result was reached a few years later in Brown _v._ Houston,[557] where it was held that coal transported down the Mississippi from Pennsylvania had been validly subjected by Louisiana to a general _ad valorem_ property tax, having "come to its place of rest, for final disposal or use," and hence become "a part of the general mass