43 U.S.C. § 906
In all cases where persons being citizens of the United States, or who have declared their intentions to become such, in accordance with the naturalization laws of the United States, are in possession of any of the lands affected by any such grant and resumed by and restored to the United States, under deed, written contract with, or license from, the State or corporation to which such grant was made, or its assignees, executed prior to January 1, 1888, or where persons may have settled said lands with bona fide intent to secure title thereto by purchase from the State or corporation when earned by compliance with the conditions or requirements of the granting Acts of Congress they shall be entitled to purchase the same from the United States, in quantities not exceeding three hundred and twenty acres to any one such person, at the rate of $1.25 per acre, at any time prior to January 1, 1899, and on making said payments to receive patents therefor, and where any such person in actual possession of any such lands and having improved the same prior to the 1st day of January, 1890, under deed, written contract, or license as aforesaid, or his assignor, has made partial or full payments to said railroad company prior to said date, on account of the purchase price of said lands from it, on proof of the amount of such payments he shall be entitled to have the same, to the extent and amount of $1.25 per acre, if so much has been paid, and not more, credited to him on account of and as part of the purchase price herein provided to be paid the United States for said lands, or such persons may elect to abandon their purchases and make claim on said lands under the homestead law and as provided in section 905 of this title: Provided, That in all cases where parties, persons, or corporations, with the permission of such State or corporation, or its assignees, are in the possession of and have made improvements upon any of the lands resumed and restored, and are not entitled to enter the same under the provisions of sections 904 to 907 of this title, such parties, persons, or corporations shall have six months in which to remove any growing crop, and within which time they shall also be entitled to remove all buildings and other movable improvements from said lands: Provided further, That the provisions of this section shall not apply to any lands situated in the State of Iowa on which any person in good faith has made or asserted the right to make a preemption or homestead settlement: And provided further, That nothing in sections 904 to 907 of this title contained shall be construed as limiting the rights granted to purchasers or settlers by sections 894 to 899 of this title, or as repealing, altering, or amending said sections, nor as in any manner affecting any cause of action existing in favor of any purchaser against his grantor for breach of any covenants of title.
Actual residence upon the lands by persons claiming the right to purchase the same shall not be required where such lands have been fenced, cultivated, or otherwise improved by such claimants, and such persons shall be permitted to purchase two or more tracts of such lands by legal subdivisions, whether contiguous or not, but not exceeding three hundred and twenty acres in the aggregate.
Nothing herein contained shall be so construed as to interfere with any adverse claim that may have attached to the lands or any part thereof.
43 U.S.C. § 906