It shall be the duty of the state auditor, as the supervisor of county audits, to examine annually the assessed valuation figures of the various counties immediately upon the certification of same by the state equalizing agency and to ascertain if any county shall have changed classifications as determined in this chapter. In case it shall be found that any county has met the requirements of reclassification as set forth in this chapter, it shall be the duty of the state auditor within thirty days after said certification to notify officially all county elected officers and the county officials charged with the supervision of elections of the change in status of the county.