Okla. Const. art. XVIII, § 3(a)

Any city containing a population of more than two thousand inhabitants may frame a charter for its own government, consistent with and subject to the Constitution and laws of this State, by causing a board of freeholders, composed of two from each ward, who shall be qualified electors of said city, to be elected by the qualified electors of said city, at any general or special election, whose duty it shall be, within ninety days after such election, to prepare and propose a charter for such city, which shall be signed in duplicate by the members of such board or a majority of them, and returned, one copy of said charter to the chief executive officer of such city, and the other to the Register of Deeds of the county in which said city shall be situated. Such proposed charter shall then be published in one or more newspapers published and of general circulation within said city, for at least twenty-one days, if in a daily paper, or in three consecutive issues, if in a weekly paper, and the first publication shall be made within twenty days after the completion of the charter; and within thirty days, and not earlier than twenty days after such publication, it shall be submitted to the qualified electors of said city at a general or special election, and if a majority of such qualified electors voting thereon shall ratify the same, it shall thereafter be submitted to the Governor for his approval, and the Governor shall approve the same if it shall not be in conflict with the Constitution and laws of this State. Upon such approval it shall become the organic law of such city and supersede any existing charter and all amendments thereof and all ordinances inconsistent with it. A copy of such charter, certified by the chief executive officer, and authenticated by the seal of such city, setting forth the submission of such charter to the electors and its ratification by them shall, after the approval of such charter by the Governor, be made in duplicate and deposited, one in the office of the Secretary of State, and the other, after being recorded in the office of said Register of Deeds, shall be deposited in the archives of the city; and thereafter all courts shall take judicial notice of said charter. The charter so ratified may be amended by proposals therefor, submitted by the legislative authority of the city to the qualified electors thereof (or by petition as hereinafter provided) at a general or special election, and ratified by a majority of the qualified electors voting thereon, and approved by the Governor as herein provided for the approval of the charter.