Mr. Justice Black
delivered the opinion of the Court.
In United States v. California (the first California case), 332 U. S. 19 (1947), we held that the States did not own the submerged lands off their coastlines and that the United States had paramount rights in these lands. Some States violently objected to this decision claiming that they had historically owned at least out to a distance of three geographical miles from their coastlines; others asserted a historical claim out to three marine leagues from their coastlines. Responding to these objections, Congress in 1953 passed the Submerged Lands Act, 67 Stat. 29, 43 U. S. C. §§ 1301-1315, which makes two entirely separate types of grants of submerged land to the States. The first is an unconditional grant allowing each coastal State to claim a seaward boundary out to a line three geographical miles distant from its “coast line.” The second is a grant conditioned upon a State’s prior history. It allows those States bordering on the Gulf of Mexico, which at the time of their entry into the Union had a seaward boundary beyond three miles, to claim this historical boundary “as it existed at the time such State became a member of the Union,” but with the maximum limitation that no State may claim more than “three marine leagues” (approximately nine miles). In United States v. Louisiana, 363 U. S. 1 (1960), we held that Texas qualified for this conditional three-league grant. We did not decide, however, what is the “coast line” from which this three-league grant is measured. That question was specifically reserved. Texas now claims that, for purposes of the three-league grant, its coastline extends to the seaward edge of artificial jetties constructed by it in the Gulf of Mexico and that it is entitled to lease certain submerged lands, portions of which lie more than three leagues from any part of the natural shoreline of Texas, but within three leagues of these jetties. The United States claims these portions for itself and invokes our original jurisdiction for a supplemental decree to that effect. The question we must decide is whether Congress intended that this grant, based as it is on the historical boundaries of the State, be measured from artificial jetties constructed many years after the State’s entry into the Union. For reasons to be stated we reject Texas’ contention and hold, as the Act clearly says, that its three-league claim must be measured to “such boundary as it existed at the time such State became a member of the Union.”
Texas relies heavily on this Court’s prior decision in the second California case, United States v. California, 381 U. S. 139 (1965). Our opinion there, however, dealt, not with the conditional statutory grant we have here, but with the other unconditional grant — the congressional creation of a new and standard three-mile seaward boundary for all coastal States. While some States in the past had claimed three-mile seaward boundaries — a claim explicitly rejected by this Court in the first California case, supra — Congress made it clear by the following wording in § 4 of the Submerged Lands Act that it was establishing a new standard boundary for all coastal States: “Any State admitted subsequent to the formation of the Union which has not already done so may extend its seaward boundaries to a line three geographical miles distant from its coast line . . . 67 Stat. 31, 43 U. S. C. § 1312. The decision in the second California case, supra, held that Congress had left it up to this Court to define the “coast line” from which the standard three-mile grant was to be measured. The Court then borrowed the international definition of coastline in the Convention on the Territorial Sea and the Contiguous Zone, [1964] 15 U. S. T. (Pt. 2) 1607, T. I. A. S. No. 5639, used by the United States in its foreign relations with other countries, reasoning that “[t]his establishes a single coastline for both the administration of the Submerged Lands Act and the conduct of our future international relations .... Furthermore the comprehensiveness of the Convention provides answers to many of the lesser problems related to coastlines which, absent the Convention, would be most troublesome.” United States v. California, 381 U. S. 139, 165 (1965).
Article 8 of this Convention makes the following provision for artificially constructed extensions into the sea: “For the purpose of delimiting the territorial sea, the outermost permanent harbour works which form an integral part of the harbour system shall be regarded as forming part of the coast.” [1964] 15 U. S. T. (Pt. 2) 1607, 1609. Thus, it is clear that in the case of the three-mile unconditional grant artificial jetties are a part of the coastline for measurement purposes, and if Texas were claiming under the standard three-mile grant, its argument regarding the jetties would be far more persuasive.
Texas has not claimed the standard three-mile grant, however, but has asserted ownership over three marine leagues or approximately nine miles of submerged land, and this Court has sustained that claim. United States v. Louisiana, supra. This it was allowed to do under that part of the Act providing the special conditional historical grant. There is a critical distinction, however, between this historical grant and the unconditional three-mile grant. The three-mile grant involved in the second California case is not keyed to the State’s boundary as of any particular date, but the three-league grant is keyed to a State’s boundary as of the date it entered the Union. This is clear from the words of § 2 (a) of the Act which state that the historical grant extends “to the boundary line of each such State where in any case such boundary as it existed at the time such State became a member of the Union . . . extends seaward (or into the Gulf of Mexico) beyond three geographical miles_” 67 Stat. 29, 43 U. S. C. § 1301. (Emphasis added.) This meaning is reinforced by the wording of § 4 which states that “[n]othing in this section is to be construed as questioning or in any manner prejudicing the existence of any State’s seaward boundary beyond three geographical miles if it was so provided by its constitution or laws prior to or at the time such State became a member of the Union . . . .” 43 U. S. C. § 1312. (Emphasis added.) This historical grant of three marine leagues is, through § 2 (b) of the Act, made to apply only to those States bordering the Gulf of Mexico. 43 U. S. C. § 1301.
In effect what Congress has done is to take into consideration the special historical situations of a few Gulf States and provide that where they can prove ownership to submerged lands in excess of three miles at the time they entered the Union, these historical lands will be granted to them up to a limitation of three marine leagues. No new state boundary is being created, but a State which qualifies simply is being given the same area it had when it entered the Union. Unlike the three-mile grant where this Court held that Congress left boundary definitions up to it, here Congress granted land the boundaries of which are determined by fixed historical facts. This is clear from the wording of the statute itself. In making the three-mile grant Congress speaks in terms of “three geographical miles distant from its coast line.” 43 U. S. C. § 1312. (Emphasis added.) In the three-league grant, however, the term “coast line” is omitted and in its place the word “boundary” is used with the following express qualification: “as it existed at the time such State became a member of the Union . . . ,” No definitions are required by this Court and there is no need to resort to international law; Texas has simply been given that amount of submerged land it owned when it entered the Union.
Thus, the State of Texas, which has been allowed by the United States to claim a larger portion of submerged lands because of its historical situation, is limited in its claim by fixed historical boundaries. It may not combine the best features of both grants in order to carve out the largest possible area for itself. If it wishes to take advantage of the present three-mile grant then it may use its present coastline as defined by Article 8 of the Convention on the Territorial Sea and the Contiguous Zone, supra, to include artificial jetties. But if Texas wishes to take under the more expansive historical grant, it must use boundaries as they existed in 1845 when Texas was admitted to the Union. At that time there were no artificial jetties in existence so obviously they are not considered.
It cannot be ignored that the application of the Convention to Texas here would allow Texas, unlike all other States except Florida, to expand its own state boundaries beyond the congressional limitation simply because of a rule governing the relationships between maritime nations of the world. This is a domestic dispute which must be governed by the congressional grant. There is no reason why an international treaty should be applied when it simply works to take away land from the United States in order to give to Texas more land than it ever claimed historically. We cannot believe that Congress intended such a result.
Thus, we hold today that the congressional grant to Texas of three marine leagues of submerged land is measured by the historical state boundaries “as they existed” in 1845 when Texas was admitted into the Union. The United States is entitled to a supplemental decree to this effect, and we grant 60 days to each of the parties in which to submit proposed supplemental decrees for our consideration.
The Chief Justice and Mr. Justice Marshall took no part in the consideration or decision of this case.
Louisiana was the only State to raise the question and our answer was as follows: “We decide now only that Louisiana is entitled to submerged-land rights to a distance no greater than three geographical miles from its coastlines, wherever those lines may ultimately be shown to be.” 363 U. S., at 79. (Emphasis added.)
In United States v. Florida, 363 U. S. 121 (1960), we held that Florida also was entitled to the historical three-league grant. Since historical claims by the other Gulf States of Louisiana, Mississippi, and Alabama were rejected in United States v. Louisiana, 363 U. S. 1 (1960), Texas and Florida are the only two States which qualify for the expansive grant of three marine leagues instead of the grant of three miles.