Opinion of the Court.

requested to answer it, waiving such answer being on oath, and that upon the final hearing this court will definitely settle the boundary between the States at the said several bridges.

To this bill the State of Illinois appeared by its attorney general and filed its answer, which denied that the boundary line between the States of Iowa and Illinois is the middle of the Mississippi River, and insisted that it is the middle of the steamboat channel, or channel commonly used by boats in carrying the commerce of the river, whether east or west of the middle of the river. It admitted that the State and its municipalities claimed the right to tax and did tax bridges and other structures in the river to the middle of the steamboat channel or channel of commerce, whether such channel was east or west of the middle of the main body or arm of the river, and did assess and tax the Keokuk and Hamilton bridge to its draw and west of the middle of the main body or arm of the river; and that the steamboat channel or channel of commerce is first near one shore and then near the other, and at other places nearly across the river. But it denied the right of the State of Iowa to tax the bridges mentioned crossing the Mississippi River to any point east of the middle of the steamboat channel, or channel of commerce of that river.

To the answer a replication was filed by the State of Iowa. At the time of filing its answer the State of Illinois filed also its cross-bill, in which it alleges that there exist nine bridges across the Mississippi River between the States, the most southern of which is the Keokuk and Hamilton Railroad bridge and the most northern, the Dunlieth and Dubuque Bridge Company's railroad bridge.

That for the purposes of taxation the State of Illinois and its municipalities claim the right to assess and tax the respective bridges to the middle of the channel of commerce or steamboat channel, that is, the channel usually used by steamboats and other crafts navigating the river; and that on the part of the State of Iowa and its municipalities it is claimed that each State has the right to assess and tax to the middle of the main arm or body of the river, regardless of where the channel of commerce or steamboat channel may be.

Opinion of the Court.

That the Supreme Court of Iowa, in the case of The Dun lieth and Dubuque Bridge Company v. The County of Dubuque, (55 Iowa, 558,) held that the authorities in Iowa have the right to tax such structures to the middle of the main arm or body of the stream and no further, though at the point where such structure is situated the channel or part of the river followed by steamboat men in navigating the river is far east of the middle of such main body of the stream.

That following the decision in that case, the authorities in Iowa assess and tax such structures to the middle of the main body of the river.

That at the point of the location of the Keokuk and Hamilton bridge the main body of the river, before the construction of the bridge, was between the Iowa shore at Keokuk, Lee. County, Iowa, and the west shore of Island No. Four, located in the city of Hamilton, Hancock County, Illinois, a breadth of about 3042 feet; that in constructing the bridge a solid approach is extended from the shore at Keokuk into the river 200 feet, and from the shore on Island No. Four, in Illinois, about 700 feet, and the main body of the river confined between the abutments to the bridge 2192 feet apart, and the bridge consists of the east and west abutments, eleven piers, a draw next to the west or Iowa abutment of 380 feet, and ten spans, together 1812 feet.

That the middle of the steamboat channel, or that part of the river usually traversed by steamboat men in navigating the river, is at or near the east end of the draw or pivot span, about 380 feet from the west abutment and 1812 feet from the east abutment.

That the assessor in Illinois in assessing the bridge values the bridge to the east end of the draw and assesses the same against that part of the bridge in Illinois, and the authorities. in Iowa value and assess the bridge to the middle thereof, 1096 feet east from the west abutment, as in the State of Iowa; that thereby 716 feet of the bridge are valued and assessed both in Illinois and Iowa; that litigation is now pending in the lower courts between the bridge company and the authorities over the assessments, and that the same

Opinion of the Court.

trouble and complications are liable to arise over the assessment of any other of the bridges.

To the end, therefore, that the boundary line between the States of Illinois and Iowa at said several bridges may be defined and settled, the State of Illinois prays that the State of Iowa be made defendant to this cross-bill, and required to answer it, and that upon the final hearing the court will define and establish at each of the bridges the boundary lines between the States of Illinois and Iowa, to which points the respective States may tax. To this cross-bill the defendant, the State of Iowa, answered, admitting the existence of nine bridges across the Mississippi River, where it forms the boundary between the States of Illinois and Iowa, and that the State of Illinois and its several municipalities bordering upon the river claim the right to tax said bridges from the Illinois shore of the river to the middle of the channel of commerce or steamboat channel, and that the State of Iowa and its municipalities bordering on the river claim the right to tax and do tax the several bridges to the middle of the main arm or body of the river, regardless of where the channel of commerce or steamboat channel, that is, that part of the river usually traversed by steam or other vessels carrying the commerce of the river, may be. It therefore prays that upon the final hearing the boundary lines between the two States may be established, to which the respective States may

tax.

By setting down the case for hearing on the bill, answer and replication, (without taking any testimony,) and on the cross-bill and the answer to it, all the facts alleged in the answer to the original bill, as were as those alleged in the crossbill and not denied in the answer, are thereby admitted.

When a navigable river constitutes the boundary between two independent States, the line defining the point at which the jurisdiction of the two separates is well established to be the middle of the main channel of the stream. The interest of each State in the navigation of the river admits of no other line. The preservation by each of its equal right in the navigation of the stream is the subject of paramount interest. It

Opinion of the Court.

is, therefore, laid down in all the recognized treatises on international law of modern times that the middle of the channel of the stream marks the true boundary between the adjoining States up to which each State will on its side exercise jurisdiction. In international law, therefore, and by the usage of European nations, the term "middle of the stream," as applied to a navigable river, is the same as the middle of the channel of such stream, and in that sense the terms are used in the treaty of peace between Great Britain, France and Spain, concluded at Paris in 1763. By the language, “a line drawn along the middle of the river Mississippi from its source to the river Iberville," as there used, is meant along the middle of the channel of the river Mississippi. Thus Wheaton, in his Elements of International Law, (8th ed. § 192,) says:

"Where a navigable river forms the boundary of conterminous States, the middle of the channel, or Thalweg, is generally taken as the line of separation between the two States, the presumption of law being that the right of navigation is common to both; but this presumption may be destroyed by actual proof of prior occupancy and long undisturbed possession, giving to one of the riparian proprietors the exclusive title to the entire river."

And in § 202, whilst thus stating the rule as to the boundary line of the Mississippi River being the middle of the channel, he states that the channel is remarkably winding, "crossing and recrossing perpetually from one side to the other of the general bed of the river."

Mr. Creasy, in his First Platform on International Law, § 231, p. 222, expresses the same doctrine. He says:

"It has been stated that, where a navigable river separates neighboring States, the Thalweg, or middle of the navigable channel, forms the line of separation. Formerly a line drawn along the middle of the water, the medium filum aquæ, was regarded as the boundary line; and still will be regarded prima facie as the boundary line, except as to those parts of the river as to which it can be proved that the vessels which navigate those parts keep their course habitually along some

Opinion of the Court.

channel different from the medium filum. When this is the case, the middle of the channel of traffic is now considered to be the line of demarcation."

Mr. Creasy also refers to the language of Dr. Twiss on the same subject, who observes that "Grotius and Vattel speak of the middle of the river as the line of denarcation between two jurisdictions, but modern publicists and statesmen prefer the more accurate and more equitable boundary of the navigable Midchannel. If there be more than one channel of a river, the deepest channel is the Midchannel for the purposes of territorial demarcation; and the boundary line will be the line drawn along the surface of the stream corresponding to the line of deepest depression in its bed. The islands on either side of the Midchannel are regarded as appendages to either bank; and if they have once been taken possession of by the nation to whose bank they are appendant, a change in the Midchannel of the river will not operate to deprive that nation of its possession, although the water-frontier line will follow the change of the Midchannel."

Halleck in his Treatise on International Law, c. 6, § 23, is to the same effect. He says: "Where the river not only separates the conterminous States, but also their territorial jurisdictions, the thalweg, or middle channel, forms the line of separation through the bays and estuaries through which the waters of the river flow into the sea. As a general rule, this line runs through the middle of the deepest channel, although it may divide the river and its estuaries into two very unequal parts. But the deeper channel may be less suited, or totally unfit for the purposes of navigation, in which case the dividing line would be in the middle of the one which is best suited and ordinarily used for that object."

Woolsey in his International Law, § 58, repeats the same doctrine and says: "Where a navigable river forms the boundary between two States, both are presumed to have free use of it, and the dividing line will run in the middle of the channel, unless the contrary is shown by long occupancy or agreement of the parties. If a river changes its bed, the line through the old channel continues, but the equitable right to the free