Mississippi Code Title 25. Public Officers and Employees; Public Records § 25-3-15

It is hereby further provided that, in any county of the state having producing oil or gas wells, the total valuation of such oil or gas produced, as reported by the State Tax Commission for the last preceding calendar year, may be combined with the total assessed valuation of said county in computing its category for the purpose of fixing the salary of the members of the board of supervisors of said county; provided that in any county wherein twenty-five percent (25%) or more of the real property of the county is owned by an agency of the federal government, and consequently exempt from ad valorem taxes, the salary of the members of the board of supervisors in each such county shall be that established by the next highest rate from that determined by the total assessed value of the property of the county.