system: You are a legal assistant. Answer concisely and accurately. When legal text is provided, rely on it and do not invent facts.

user: Read the following U.S. Supreme Court case excerpt and classify it into the correct legal issue area. Excerpt: 399 U.S. 146 90 S.Ct. 2187 26 L.Ed.2d 487 ILLINOISv.MISSOURI. No. 18, Original. Supreme Court of the United States June 22, 1970 DECREE 1 The Court having referred this case to a Special Master who has filed his Report, and the parties having agreed as to the form of the decree, the Findings of Fact and Conclusions of Law are hereby adopted, and It is ordered, adjudged, and decreed that: 2 (1) The boundary line between the States of Illinois and Missouri for the geographical area involved in this action is hereby determined and decreed to consist of the following legal description: 3 Beginning at a point in present centerline of the Mississippi River at the intersection of the centerline of the Old Mississippi River said point being designated as the Southeasterly corner of Kaskaskia Island; thence following the centerline of the slough which is the approximate centerline of the Old Mississippi River, described more particularly by the following courses and distances: § 39°30' W, 2100 feet; thence § 55°30' W, 900 feet; thence § 34°30' W, 850 feet; thence N 83°00' W, 500 feet; thence § 61°00' W, 1000 feet; thence § 42°30' W, 2500 feet; thence § 37°00' W, 4000 feet; thence § 45°00' W, 2000 feet; thence § 56°30' W, 4600 feet; thence § 63°00' W, 2150 feet; thence § 79°30' W, 1525 feet; thence N 86°30' W, 4500 feet; thence N 70°00' W, 5050 feet; thence N 57°30' W, 3850 feet; thence N 46°00' W, 1550 feet; thence N 24°00' W, 5650 feet; thence N 39°00' W, 1800 feet; thence N 17°00' W, 1900 feet; thence N 25°30' W, 3150 feet; thence N 32°00' W, 1580 feet; thence N 4°30' W, 3250 feet; thence N 53°45' E, 3300 feet; thence N 69°00' E, 1050 feet; thence 19°00' E, 2350 feet; thence N 75°00' E, 350 feet to a point at the northwest corner of Kaskaskia Island; thence § 47°00' E, 250 feet; thence N 81°00' E, 1050 feet; thence § 78°00' E, 600 feet; thence N 88°45' E, 1551 feet; thence N 70°45' E, 709 feet; thence N 48°30' E, 2986 feet; thence N 51°45' E, 627 feet; thence N 81°45' E, 990 feet; thence N 62°45' E, 495 feet; thence N 40°00' E, 2937 feet; thence N 28°00' E, 528 feet; thence N 04°00' E, 429 feet; thence N 12°00' W, 759 feet; thence N 6°00' E, 412 feet; thence N 33°00' E, 264 feet; to a point which interests the centerline of a slough at the south side of Beaver Island; thence along the centerline of said slough § 85°00' W, 924 feet; thence § 79°00' W, 775 feet; thence N 88°00' W, 1452 feet; thence N 23°00' W, 825 feet; thence N 20°00' W, 3000 feet to the centerline of the Mississippi River. 4 (2) In incidence to the establishment of such boundary line, and upon Missouri's disclaimer herein, the territorial and sovereignty right claimed by Illinois to the body of land given identification in the evidence as 'Kaskaskia Island' is hereby confirmed as against Missouri and decreed to exist in Illinois. 5 (3) In further incidence to the boundary establishment made, the territorial and sovereignty right claimed by Illinois to the body of land given identification in the evidence as 'Beaver Island' is hereby confirmed as against Missouri and decreed to exist in Illinois. 6 (4) In similar incidence, the territorial and sovereignty right claimed by Missouri to each of the two bodies of land given identification severally in the evidence as 'Cottonwoods' and 'Roth Island' is hereby sustained as against Illinois and decreed to exist in Missouri. 7 (5) The boundary description decreed in paragraph (1) hereof is taken from Attachment 'C' of the parties' stipulation as being agreed upon by them to be appropriate and accurate for dispositional use in the event of and in relation to the result here reached. The bodies of land as to which Illinois' rights are confirmed in paragraphs (2) and (3) hereof are located on Illinois' side of the boundary line fixed, and those as to which Missouri's rights are sustained in paragraph (4) hereof are located upon Missouri's side thereof, so that no separate description is here necessary as to any of these bodies in order to effectuate the rights decreed in respect to them. 8 (6) The costs of the suit shall be assessed equally against the parties. 9 Mr. Justice BLACKMUN took no part in the entry of this decree.

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