N.D. Cent. Code § 11-15-25
A sheriff or the sheriff's deputy shall receive for transporting persons committed to the custody of the department of corrections and rehabilitation or to the state hospital the mileage prescribed in this chapter. The sheriff or deputy shall utilize the least expensive method of transportation, and the mileage allowed must be based only upon the use of the least expensive method of transportation and may be paid only after the filing with the county auditor of an itemized statement verified by affidavit showing the mileage traveled, the manner in which traveled, the days traveled, and the purpose of the travel and showing that the method of travel was the least expensive method of transportation. The county auditor shall submit the statement and affidavit to the board of county commissioners. The county auditor may not pay the claim until the claim is approved by the board.
N.D.C.C. § 11-15-25