Mr. Justice Rehnquist
delivered the opinion of the Court.
In June 1972, the Rosebud Sioux Tribe sued in the United States District Court for the District of South Dakota to obtain a declaratory judgment that the original boundaries of their reservation, as defined in the Act of March 2, 1889, 25 Stat. 888, had not been diminished by three subsequent Acts of Congress passed in 1904, 1907, and 1910 respectively.1 The District Court, noting that “[f]rom the time these acts were passed, these [four] counties have been treated as outside the Rosebud Sioux Reservation by the settlers, their descendants, the State of South Dakota and the federal courts,” 375 F. Supp. 1065, 1084, denied relief. It concluded that Congress had intended to diminish the Reservation so as to exclude the four counties in South Dakota affected by the 1904, the 1907, and the 1910 Acts. The United States Court of Appeals for the Eighth Circuit, in a careful and comprehensive opinion, affirmed the judgment of the District Court. 521 F. 2d 87. We granted certiorari, 425 U. S. 989, to review this determination in the light of our recent decisions in DeCoteau v. District County Court, 420 U. S. 425 (1975), and Mattz v. Arnett, 412 U. S. 481 (1973). Since we conclude that the three Acts [586]*586of Congress in question satisfy the requirement that “[a] congressional determination to terminate [an Indian reservation] must be expressed on the face of the Act or be clear from the surrounding circumstances and legislative history,” Mattz v. Arnett, supra, at 505, we affirm the judgment of the Court of Appeals.
I
When established, the Rosebud Indian Reservation contained somewhat over 3.2 million acres, and covered all or a portion of what later became five counties in South Dakota: Gregory, Tripp, Lyman, Mellette, and Todd. The three Acts we are asked to construe successively disposed of all unallotted lands in Gregory County (1904 Act), in Tripp and Lyman Counties (1907 Act), and in Mellette County (1910 Act). Only Todd County remains unaffected by these post-1889 enactments. The contention of the Rosebud Sioux Tribe is that these Acts, while opening up the unallotted land outside of Todd County to non-Indian settlement, did not thereby change the Reservation boundaries, which continued to encompass these five counties.
In determining whether or not the 1889 Reservation boundaries were subsequently diminished by congressional enactments, we are guided by well-established legal principles. The underlying premise is that congressional intent will control. DeCoteau v. District County Court, supra, at 444, 449; United States v. Celestine, 215 U. S. 278, 285 (1909). In determining this intent, we are cautioned to follow “the general rule that ‘[d]oubtful expressions are to be resolved in favor of the weak and defenseless people who are the wards of the nation, dependent upon its protection and good faith.' ” McClanahan v. Arizona State Tax Comm’n, 411 U. S. 164, 174 (1973), quoting Carpenter v. Shaw, 280 U. S. 363, 367 (1930); see also Mattz v. Arnett, supra, at 505. The mere fact that a reservation has been opened to settlement does not necessarily mean that the opened area has lost its reservation [587]*587status. Mattz v. Arnett, supra; see also Seymour v. Superintendent, 368 U. S. 351 (1962). But the “general rule” does not command a determination that reservation status survives in the face of congressionally manifested intent to the contrary. DeCoteau v. District County Court, supra. In all cases, “the face of the Act,” the “surrounding circumstances,” and the “legislative history,” are to be examined with an eye toward determining what congressional intent was. Mattz v. Arnett, supra, at 505.
Applying these principles to the facts of this case, we conclude that the Acts of 1904, 1907, and 1910 did clearly evidence congressional intent to diminish the boundaries of the Rosebud Sioux Reservation. The parties agree that an amendment to the 1889 Treaty, which provided for a fixed-sum payment and which was approved by three-fourths of the Rosebud Sioux Tribe’s adult males in 1901, would have resulted in the diminution of the Rosebud Reservation boundaries. Congress did not, however, approve the 1901 amendment to the Treaty which the Tribe had ratified. The Tribe contends that, lacking tribal ratification and a fixed-sum provision, the later Acts were ineffectual to accomplish this same result. In the Tribe’s view, the absence of these two factors vitally distinguishes the Acts in question from the otherwise similar Act examined in DeCoteau v. District County Court, supra. Because of the reasons hereafter set forth in greater detail, we conclude that, although the Acts of 1904, 1907, and 1910 were unilateral Acts of Congress without the consent of three-quarters of the members of the tribe required by the original Treaty,2 that fact does not have any direct bearing on the question of whether Congress by these later Acts did intend to diminish the Reservation boundaries. By the time of [588]*588the first of these Acts, in 1904, Congress was aware of the decision of this Court in Lone Wolf v. Hitchcock, 187 U. S. 553 (1903), which held that Congress possessed the authority to abrogate unilaterally the provisions of an Indian treaty. We also conclude that the changed method of payment is not conclusive with respect to congressional intent. Although the later Acts of Congress made less secure provisions for payment to the Tribe for the lands in question than did the 1901 Treaty, their language with respect to the reservation status of the opened lands was identical with or derivative from the language used in that proposed amendment.3 The language was also substantially equivalent to that used in the executed agreement involved in DeCoteau. We agree with the Court of Appeals and the District Court that this language not only opened the land for settlement, but diminished the boundaries of the Reservation pro tanto.4
[589]*589II
The Rosebud Sioux are one of the tribes of Indians of the Sioux Nation. The Treaty of April 29, 1868, 15 Stat. 635, set aside all the land in South Dakota west of the Missouri River as the Great Sioux Reservation, consisting of some 25 million acres. Article 12 of the Treaty provided that no subsequent treaty for the cession of any part of the reservation would be valid without the written consent of three-fourths of the adult male Indians on the reservation. Despite this provision, in 1877 approximately 7.5 million acres, consisting of the Black Hills portion of the Great Sioux Reservation, were removed from the Reservation by the Act of February 28, 1877, 19 Stat. 254. See Sioux Tribe of Indians v. United States, 97 Ct. Cl. 613 (1942), cert. denied, 318 U. S. 789 (1943). Of the remaining Reservation, approximately one-half was “restored to the public domain” under the Act of March 2, 1889, 25 Stat. 896, § 21,5 while six separate Reservations were carved out of the remainder, §§ 1-6. Section 2 set apart the Rosebud Reservation, encompassing what were later organized as three full counties (Todd, Mellette, and Tripp), a major portion of Gregory County, and a small portion of Lyman.6 This Reservation, as originally delimited, contained over 3.2 million acres.
[590]*590Around the turn of the century, the “familiar forces” to which we referred in DeCoteau v. District County Court, led to demands to open up the Reservation.7 A provision in the Indian Department Appropriation Act, Mar. 3, 1901, 31 Stat. 1077, provided:
“[T]he Secretary of the Interior be, and he is hereby, authorized, in his discretion, to negotiate, through any United States Indian inspector, agreements with any Indians for the cession to the United States of portions of their respective reservations or surplus unallotted lands, any agreements thus negotiated to be subject to subsequent ratification by Congress.”
Shortly thereafter Inspector James McLaughlin was instructed by the Commissioner of Indian Affairs to begin “negotiations with the Indians of the Rosebud reservation, in South Dakota, for the cession of the unallotted eastern portion of their reserve.” Letter dated Mar. 19, 1901, from W. A. Jones, Commissioner, Office of Indian Affairs, Department of Interior. Following meetings with members of the Tribe during the spring and summer of 1901, Inspector McLaughlin obtained the written consent of three-fourths of the [591]*591male Indian adults to the cession of some 416,000 acres of unallotted land in Gregory County for the sum of $1,040,000, subject to congressional ratification.8 The negotiated Agreement, however, was never ratified,9 “because of the fact that it provided that the Government should pay for the lands outright . . . ." 38 Cong. Rec. 1423 (1904) (remarks of Rep. Burke) .10
What is important for our purposes is the undisputed fact that the 1901 Agreement, had it been ratified by Congress, would have disestablished that portion of the Rosebud Reservation which lay in Gregory County. Inspector McLaughlin explained to the Tribe that “[t]he cession of Gregory County” by ratification of the Agreement “will leave your reservation a compact, and almost square tract, and would leave your [592]*592reservation about the size and area of Pine Ridge Reservation.” 11 It is conceded that his description was correct; the effect and intent of the 1901 Agreement, if ratified, would have been to change the Reservation boundaries. As we noted in DeCoteau v. District County Court, 420 U. S., at 445, in construing virtually identical language: “The Agreement’s language . . . was precisely suited to this purpose [of disestablishment].” In this Agreement, therefore, we have—unlike the situation in Mattz v. Arnett, 412 U. S. 481 (1973)—an unmistakable baseline purpose of disestablishment.
An examination of the legislative processes which resulted in the 1904 Act convinces us, as it did the lower courts, that this purpose was carried forth and enacted. Because of the history of the 1901 Agreement, the 1904 Act cannot, and should not, be read as if it were the first time Congress had addressed itself to the diminution of the Rosebud Reservation.
In 1903, new bills were introduced, and subsequently reported from committee in both chambers of Congress, which proposed “to adopt a new policy in acquiring lands from the Indians [by] provid[ing] that the lands shall be disposed of to settlers . . ., and to be paid for by the settlers, and the money to be paid to the Indians only as it is received . . . from the settlers.” 12 The Senate bill, S. 7390, passed the Senate in February, 36 Cong. Rec. 2748 (1903), but the 57th Congress expired before the House could give it consideration. In line with the changes in S. 7390, which related to the method of payment, Inspector McLaughlin was subsequently instructed to go to the Rosebud Reservation to negotiate a new [593]*593agreement.13 He explained to the Rosebud Tribe: “I am here to enter into an agreement which is similar to that of two years ago, except as to the manner of payment . . . . You will still have as large a reservation as Pine Ridge after this is cut off.” 14
Inspector McLaughlin failed to get three-fourths of the adult male Indians to consent to this new method of payment, although he did obtain the consent of a majority, provided that the price to homesteaders be raised from $2.50 to $2.75 per acre. Agreement of Aug. 10, 1903.15 How[594]*594ever, as Inspector McLaughlin had explained to the Tribe,16 Congress understood that it was not bound by the three-fourths-consent requirement of the 1868 Treaty with the Sioux Nation. In Lone Wolf v. Hitchcock, 187 U. S., at 566, 568, this Court, dealing with the validity of a cession of tribal lands enacted in contravention of a treaty requiring three-fourths Indian consent, held:
“The power exists to abrogate the provisions of an Indian treaty, though presumably such power will be exercised only when circumstances arise which will not only justify the government in disregarding the stipulations of the treaty, but may demand, in the interest of the country and the Indians themselves, that it should do so. When, therefore, treaties were entered into between the United States and a tribe of Indians it was never doubted that the power to abrogate existed in Congress . . . .
“. . . In any event, as Congress possessed full power in the matter, the judiciary cannot question or inquire into the motives which prompted the enactment of this legislation.”
Although Inspector McLaughlin failed to garner the signatures of three-quarters of the Indians in consent of the proposed changes, Congress understandably relied on this holding as authorizing it to diminish unilaterally the Reservation boundaries.
In examining congressional intent, there is no indication [595]*595that Congress intended to change anything other than the form of, and responsibility for, payment. In recommending ratification of the 1901 Agreement, as modified, the accompanying House Report stated:
“The purpose of this bill is to ratify and amend an agreement made with the Rosebud Indians in South Dakota by Inspector James McLaughlin, dated September 14, 1901, providing for the cession to the United States of the unallotted portion of their lands in Gregory County, S. Dak., and opening the same to settlement and entry under the homestead and town-site laws.
“There is no question but what the Indians have no use for the land that is proposed to be ceded by this bill; that the tract is only a very small portion of the Rosebud Reservation, and is really only a corner of the reservation, which will be left compact and in a square tract and a reservation about equal in size to the Pine Ridge Reservation, in South Dakota.”17
On the floor of the House, Congressman Burke, the 1904 Act’s sponsor, in discussing the changes in the Agreement since [596]*5961901, made clear that the new bill was concerned only with the responsibility for payment, 38 Cong. Rec. 1423 (1904):
“Mr. BURKE. . . . In 1901 a treaty was entered into with the Rosebud Indians on the part of the United States, by which the Indians agreed to sell to the Government this land for $2.50 per acre. That treaty was transmitted to Congress, and because of the fact that it provided that the Government should pay for the lands outright and then take the chance of the Treasury being reimbursed by disposing of the lands to settlers, it never got further than through the Committee on Indian Affairs, which unanimously reported it favorably. It was never given consideration in the House.
“Toward the concluding days of the last session of Congress a new bill was prepared, substantially as this bill now provides, and that bill provided that the lands should be ceded by the Indians to the Government, disposed of to settlers under the provisions of the homestead law, the price to be fixed at $2.50 an acre, as was provided in the original treaty. . . . This bill is substantially the same as the bill which I have just referred to . . . ."
The bill itself, as introduced and passed by both Houses, incorporated the entire text of the 1903 Agreement, which itself followed the 1901 Agreement except that: (1) the Indians were not guaranteed any consideration for the land except with respect to the 16th and 36th sections (school sections), but were to be paid only as the lands were actually sold to settlers; (2) the United States did not guarantee to find purchasers but agreed only to “act as trustee for said Indians to dispose of said lands.” 18 In particular, the 1904 [597]*597Act incorporated verbatim the language of immediate cession of the 1901 Agreement:
“The said Indians belonging on the Rosebud Reservation, South Dakota, for the consideration hereinafter named, do hereby cede, surrender, grant, and convey to the United States all their claim, right, title, and interest in and to all that part of the Rosebud Indian Reservation now remaining unallotted, situated within the boundaries of Gregory County . . . ." 33 Stat. 256.
As in DeCoteau v. District County Court, 420 U. S., at 445, this language is “precisely suited” to disestablishment.
Petitioner, however, objects that a “cession” requires bilateral consent, and the failure of Inspector McLaughlin to gain the approval of three-quarters of the male adult Indians vitiates any “cession.” As a matter of strict English usage, petitioner is undoubtedly correct: “cession” refers to a voluntary surrender of territory or jurisdiction, rather than a withdrawal of such jurisdiction by the authority of a superior sovereign. But as Mr. Justice (then Judge) Holmes commented, we are not free to say to Congress: “We see what you are driving at, but you have not said it, and therefore we shall go on as before.” Johnson v. United States, 163 F. 30, 32 (CA1 1908). Congress was simply repeating verbatim language from a bill ratifying the 1901 Agreement, which had made the proper use of the word “cession” because the Agreement had been approved by the Tribe. The use of the word “cession” in the 1904 Act, which was not consented to by the required extraordinary majority of the Tribe, does-not make the meaning of the Act ambiguous as between diminution of the Reservation boundaries on the one hand, and merely opening up designated lands for settlement by non-Indians, on the other. The word is technically misused, but the meaning is quite clear. It was [598]*598intended to accomplish, in 1904, precisely what it was intended to accomplish in 1901. Congress was under no misapprehension that the required portion of the Tribe had in fact approved the treaty. It knew that while a majority of the Tribe had approved it, the required extraordinary majority had not; but it had determined nonetheless to go ahead and accomplish the same result unilaterally as the Agreement would have accomplished bilaterally.19
The “bill provided that the lands should be ceded by the Indians to the Government. . . ." 38 Cong. Rec. 1423 (1904) (remarks of Rep. Burke). It is clear that Congress was relying on Lone Wolf v. Hitchcock, 187 U. S. 553 (1903), in making this unilateral declaration. There is nothing in the changed method of payment, or the failure to obtain a three-quarters vote from the Indians, which indicates that the clear intent of the 1901 Agreement to diminish the Reservation boundaries had changed between 1901 and 1904.20 The Tribe, moreover, was eventually paid for the land, supra, at 588 n. 3.
[599]*599This implied continuity in purpose from 1901 to 1904 does not, however, stand alone in indicating congressional intent. Section 4 of the 1904 Act, 33 Stat. 258, provides, in pertinent part:
“[S]ections sixteen and thirty-six of the lands hereby acquired in each township shall not be subject to entry, but shall be reserved for the use of the common schools and paid for by the United States at two dollars and fifty cents per acre, and the same are hereby granted to the State of South Dakota for such purpose . . . ."
When North and South Dakota were admitted into the Union, § 10 of the admitting Act, Act of Feb. 22, 1889, 25 Stat. 679, provided, in pertinent part:
“[U]pon the admission of each of said States into the Union sections numbered sixteen and thirty-six in every township of said proposed States . . . are hereby granted to said States for the support of common schools . . . : Provided, That the sixteenth and thirty-sixth sections embraced in permanent reservations for national pur[600]*600poses shall not, at any time, be subject to the grants . . . of this act, nor shall any land embraced in Indian, military, or other reservations of any character be subject to the grants ... of this act until the reservation shall have been extinguished and such lands be restored to, and become a part of, the public domain.”
The language of § 10 is mandatory: “nor shall” the 16th and 36th sections of lands within Indian reservations “be subject to the grants . . . until the reservation shall have been extinguished . . . .” While Congress would have had the power to establish other grants, cf. 43 U. S. C. § 856, the legislative history, in this case, demonstrates that Congress “included the provision to implement the grant in the enabling act and for no other reason.” 521 F. 2d, at 101.21 Both the House and Senate Reports explicitly noted that the “school sections” provision of what became the 1904 Act “is in conformity with the guarantee given to the State of South Dakota by Congress in the enabling act. . . .” 22 Congress, therefore, clearly thought that it was acting pursuant to § 10 of the Act of February 22, 1889, and not sub silentio adding an additional grant for [601]*601school lands located within a continuing reservation.23 The far more natural construction, then, is to read a congressional intent to disestablish Gregory County from the Rosebud Reservation, thereby making the sections available for disposition to the State of South Dakota for “school sections” under § 10 of the Act of February 22, 1889.24
[602]*602That it was clearly understood, at least by the Executive Branch, that the 1904 Act, like the 1901 Agreement, contemplated a diminution of the Reservation, is apparent from the Rosebud Proclamation of May 13, 1904, 33 Stat. 2354. In accordance with the requirement of § 2 of the 1904 Act that the land would “be disposed of under the general provisions of the homestead and town-site laws of the United States, and shall be opened to settlement and entry,” the Proclamation stated, in pertinent part:
“Whereas by an agreement between the Sioux tribe of Indians on the Rosebud Reservation, in the State of South Dakota, on the one part, and James McLaughlin, a United States Indian Inspector, on the other part, amended and ratified by act of Congress . . . the said Indian tribe ceded, conveyed, transferred, relinquished, and surrendered, forever and absolutely, without any reservation whatsoever, expressed or implied, unto the United States of America, all their claim, title, and interest of every kind and character in and to the unallotted lands embraced in the following described tract of country now in the State of South Dakota, . . .
“NOW, THEREFORE, I, THEODORE ROOSEVELT, President of the United States of America, by virtue of the power vested in me by law, do hereby declare and make known that all of the lands so as aforesaid ceded by the Sioux tribe of Indians of the Rosebud Reservation . . . will, on the eighth day of August, 1904, at 9 o’clock a. m., in the manner herein prescribed and not otherwise, be opened to entry and settlement and to disposition under the general provisions of the homestead and townsite laws of the United States.” (Emphasis supplied.)
The opening portion of the Proclamation is an unambiguous, contemporaneous, statement, by the Nation’s Chief Executive, [603]*603of a perceived disestablishment of Gregory County. It reflects, we believe, the clear import of the congressional action in the 1904 Act.
In sum, an examination of the process leading up to the enactment of the 1904 Act, as well as the language and legislative history, leads us, as it led the Court of Appeals and the District Court, to the firm conclusion that congressional intent was to exclude Gregory County from the Rosebud Reservation.25
Although the subsequent “jurisdictional history,” DeCoteau v. District County Court, 420 U. S., at 442, is not entirely clear, the single most salient fact is the unquestioned actual assumption of state jurisdiction over the unallotted lands in Gregory County since the passage of the 1904 Act, see 375 F. Supp., at 1084; Amended Complaint ¶ 21.26 Since state [604]*604jurisdiction over the area within a reservation's boundaries is quite limited, 18 U. S. C. § 1151; McClanahan v. Arizona State Tax Comm’n, 411 U. S. 164 (1973) ; Williams v. Lee, 358 U. S. 217 (1959); Worcester v. Georgia, 6 Pet. 515 (1832), the fact that neither Congress nor the Department of Indian Affairs has sought to exercise its authority over this area, or to challenge the State's exercise of authority is a factor entitled to weight as a part of the “jurisdictional history.” 27 The long[605]*605standing assumption of jurisdiction by the State over an area that is over 90% non-Indian, both in population and in land use, not only demonstrates the parties' understanding of the meaning of the Act, but has created justifiable expectations which should not be upset by so strained a reading of the Acts of Congress as petitioner urges.28 We are simply unable to conclude that the intent of the 1904 Act was other than to disestablish.
III
Having determined that the 1904 Act carried forth the intent to disestablish which was unquestionably manifested in the 1901 Agreement, our examination of the 1907 and the [606]*6061910 Acts is made easier. None of the parties really disputes that the intent of the three Acts was the same.29 Because the later Acts do vary in some respects, however, we shall explain briefly why we find a continuity of intent through the 1907 and the 1910 Acts.30
The “familiar forces" at work pressing for the opening of Indian lands did not cease with the cession of Gregory County. By late 1906, Congressman Burke was preparing a bill dealing with the “sale of that part of the reservation located in Tripp County.” 31 Inspector McLaughlin was instructed to proceed to the Rosebud Reservation to negotiate an agreement for land in Tripp County which when “ceded should be disposed of under the general provisions of the homestead and townsite laws of the United States,” and he was given suggested terms, “similar to those in the disposal [607]*607of the ceded lands in Gregory County 32 Inspector McLaughlin’s negotiations produced virtually the same result as in 1904. A 1907 Agreement, signed by a majority, but not by three-fourths, of the adult male Indians, provided that the Indians “do hereby cede, grant, and relinquish to the United States all claim, right, title, and interest in and to all that part of the Rosebud Indian Reservation [in Tripp and Lyman Counties], except such portions thereof as have been, or may hereafter be, allotted to Indians.” 33 The Secretary of the Interior recommended that Congress ratify the Agreement, Letter from E. A. Hitchcock, supra, n. 33, and the Senate Committee on Indian Affairs reported a ratification bill out, S. Rep. No. 6831, 59th Cong., 2d Sess. (1907). By this time, however, the House had already passed a second bill introduced by Congressman Burke which did not incorporate the Agreement, 41 Cong. Rec. 3103-3105 (1907) (H. R. 24987), although it did substantially incorporate the terms of the Agreement, as noted by Congressman Burke, id., at 3104:
“The bill is substantially in accordance with an agreement which has just been made with the Indians, signed by [a majority]. . . . It is along the line of the bill which passed in the Fifty-eighth Congress for the sale of that portion of this same reservation that is located in Gregory County.
[608]*608". . . They will have left, after this land is disposed of, a reservation that is substantially 50 miles square . . . .” 34
The operative language of the bill, subsequently passed by the Senate without debate, and enacted into law, 34 Stat. 1230, provided:
“[T]he Secretary of the Interior be, and he is hereby, authorized and directed, as hereinafter provided, to sell or dispose of all that portion of the Rosebud Indian Reservation in South Dakota [in Tripp and Lyman Counties], except such portions thereof as have been, or may hereafter be, allotted to Indians . . . .”
As the parties recognize, the substance of the 1907 Act is identical to the 1904 Act. Section 2 provides for the disposition of lands under the “general provisions of the homestead and town-site laws,” while § 3 specifies land purchase prices, with the proviso that “any lands remaining unsold after the said lands have been opened to entry for seven years may be sold to the highest bidder for cash, without regard to the above minimum limit of price.” 35 Section 6 provides for the purchase by the United States of sections 16 and 36 of the lands in each township and their transfer to South Dakota for “the use of the common schools.” 36 Sections 5 and 7 provide that the United States is to act as trustee for the Indians to dispose of the lands and to collect and dispense the proceeds.37
In virtually all respects, then, except for the operative language in § 1 replacing the Agreement language, the 1907 [609]*609Act is a functional twin of the 1904 Act. And, as the legislative comments make clear, supra, at 607-608, the change in § 1 language was not intended to modify or change the purposes or operation of the 1904 Act.38 We agree with the Court of Appeals’ conclusion, 521 F. 2d, at 104:
“Nothing in the language of the 1907 Act or in the surrounding circumstances and legislative history indicates a change in that congressional determination to alter the reservation boundaries which we have found in the 1904 Act.”
The 1907 Act, like the 1904 Act which preceded, it, disestablished the land in Tripp and Lyman Counties from the Rosebud Reservation.
The pressures for more land had not yet expended themselves with the passage of the 1907 Act. In late 1908, Senator Gamble submitted a new bill authorizing the sale and disposition of a portion of the surplus and unallotted lands in Mellette County and in a strip located in the eastern part of Todd County, S. 7379, 43 Cong. Rec. 65 (1908). The accompanying Senate Report noted, in proposing the opening to settlement of an area comprising about 900,000 acres, that “[t]he present area of the Rosebud Indian Reservation aggregates 1,800,000 acres.” S. Rep. No. 887, 60th Cong., 2d Sess., 1 (1909) (emphasis supplied).39 The school-sections [610]*610provision was again included in the bill, “to be paid for by the Government in conformity with the provisions of the act admitting the State of South Dakota into the Union.” Id., at 2.40 Senator Gamble was unable to have the Senate consider the bill before the term of Congress expired, and Inspector McLaughlin was once again dispatched to conduct negotiations with the Rosebud Tribe concerning the Gamble bill.41 This time, he did not seek to negotiate an agreement with the Indians, but reported back to the Secretary of the Interior the “practically unanimous” concurrence of the Indians “in the opening of the northern strip, provided the two [611]*611tiers of townships in the eastern part of Meyer [sic] County remain a part of the diminished reservation.”42
New bills were introduced similar in purpose to the original Gamble bill.43 The Secretary of the Interior recommended to Congress that the bill open only Mellette County, and not the eastern part of Todd County, and that the bill also include a provision subjecting the land to be opened “for a period of twenty-five years to all the laws of the United States prohibiting the introduction of intoxicants into the Indian country.” 44 These changes were made in S. 183, see S. Rep. No. 68, 61st Cong., 2d Sess. (1910). The Report noted, id., at 2-4:
“The present area of the Rosebud Indian Reservation aggregates about 1,800,000 acres. The lands proposed to be opened to settlement under the provisions of this bill embrace an area of about 830,000 acres. . . .
“. . . . It also provides that the Secretary of the Interior, in his discretion, may permit Indians who have allotments within the area proposed to be opened to relinquish such allotments and to receive in lieu thereof allotments anywhere within the reservation proposed to be diminished.
“Sections 16 and 36 of the lands in each township are not to be disposed of, but are reserved for the use of the common schools of the State, and these lands are to be paid for by the Government in conformity with the pro[612]*612visions of the act admitting the State of South Dakota into the Union. . . .
“Although Congress has full power to enact legislation of this character without the consent of the Indians, it was felt the Indians should be fully advised as to the provisions of the pending measure and their views should be asked in regard thereto.”
The bill was passed by the Senate on January 17, 1910, 45 Cong. Rec. 1065-1066, 1075 (1910), and the House Committee on Indian Affairs decided to adopt the Senate bill, its Report noting:
“The Rosebud Indian Reservation when set aside as a separate reservation under the Sioux act of 1889 contained something over 3,000,000 acres of land. [Then follows a description of the 1904 Act and the 1907 Act, observing that the 1907 Act was “substantially in the same form as the bill now under consideration . . . .”]
“The area comprised in the present bill is about 800,000 acres . . . . There will still be left a reservation containing about 1,000,000 acres, and as the Indians have all been allotted there is no occasion for continuing a reservation larger than it will be when Mellette County is disposed of.”45
The bill then passed the House with amendments, id., at 5473, and, after conference to reconcile differences in the House and Senate bills not material here, the bill became law on May 30, 1910.46
The 1910 Act is substantially similar to the 1907 Act, and [613]*613uses identical operative language authorizing and directing the Secretary of the Interior “to sell and dispose of all that portion of the Rosebud Indian Reservation [in present day Mellette County] except such portions thereof as have been or may be hereafter allotted to Indians . . . ." 36 Stat. 448. Because of the substantive similarity of the Acts, no useful purpose would be served in recounting the similar provisions contained in the 1910 Act. Two new provisions, however, do warrant mention. The first is a proviso in § 1, stating:
“[A]ny Indians to whom allotments have been made on the tract to be ceded may, in case they elect to do so before said lands are offered for sale, relinquish same and select allotments in lieu thereof on the diminished reservation.”
This proviso, on its face, is a strong indication of the continuing intent to disestablish the affected areas, first manifested in the 1901 Agreement. The second is the provision in § 10 of the 1910 Act, included at the suggestion of the Secretary of the Interior, subjecting the opened land “for a period of twenty-five years to all the laws of the United States prohibiting the introduction of intoxicants into the Indian country.” As there existed, in 1910, an outstanding prohibition against the introduction of intoxicants into “Indian country,” see Act of July 23, 1892, 27 Stat. 260, the most reasonable inference from the inclusion of this provision is that Congress was aware that the opened, unallotted areas would henceforth not be “Indian country,” because not in the Reservation.47
[614]*614These added provisions, as well as the clear legislative history of the 1910 Act, reflect strongly the continued intent to diminish the Reservation boundaries. We conclude that [615]*615the 1910 Act continued the policies of the prior two Acts, and Mellette County was thereby detached from the Reservation.
IV
The intent of Congress in the 1904, the 1907, and the 1910 Acts was to change the boundaries of the original 1889 Rosebud Reservation. Much has changed since then, and if Congress had it to do over again it might well have chosen a different course. But, as we observed in DeCoteau v. District County Court, 420 U. S., at 449: “[O]ur task here is a narrow one. . . . [W]e cannot remake history.” 48 Affirmed.