Okla. Stat. tit. 19, § 19-148: Population, how determined

The salaries of all county officers shall be based upon the

federal census of 1910, and each additional ten (10) years

thereafter, or upon any census taken subsequent to 1910, by order of

the board of county commissioners under and by virtue of Section

415, Revised Laws of Oklahoma, 1910, and under the supervision of

the Census Bureau of the United States Government: Provided that

when any unorganized territory is attached to any county for

judicial purposes, the population of such unorganized territory

shall be added to the population of said county in fixing the amount

of such salary.