N.D. Cent. Code § 10-13-04
All persons who are not receiving central station service and who reside in rural areas proposed to be served by a cooperative organized under this chapter shall be eligible to membership in the cooperative. No person other than the incorporators shall be, become, or remain a member of a cooperative unless such person shall use or agree to use electrical energy or the facilities, supplies, equipment, and services furnished by a cooperative.
"Rural area" means any area not included within the boundaries of an incorporated city having a population in excess of two thousand five hundred inhabitants at the time a corporation or cooperative commences to operate electric facilities or to furnish electric energy in such an area, and includes both the farm and nonfarm population thereof. No change thereafter in the population of a rural area, as defined herein, regardless of the reason for such change, shall operate to affect in any way its status as a rural area for the purposes of this chapter.
An electric cooperative organized under this chapter may become a member of another such electric cooperative and may avail itself fully of the facilities and services thereof.
N.D.C.C. § 10-13-04