Okla. Stat. tit. 18, § 438.13

The bylaws may provide for the division of the territory served or to be served by a cooperative into two or more districts for the nomination and election of trustees and the election and functioning of district delegates. Such delegates, who shall be members, may nominate and elect trustees. The bylaws shall prescribe the boundaries of the districts, or the manner of establishing such boundaries, and the manner of changing such boundaries, and the manner in which such districts shall function. No member at any district meeting and no district delegate at any meeting shall vote by proxy or by mail. Laws 1953, p. 488, § 13.