55 ILCS 5/3-1001
In all counties containing less than 3,000,000 and over 70,000 inhabitants by the last federal census, there is created the office of county auditor, whose term of office shall be 4 years and until his or her successor is elected and qualified. The nomination and election shall be subject to the general election laws of the State. Each county auditor shall take office the first day of the month following the month of his or her election on which the office of the county auditor is required, by statute or by action of the county board, to be open. The qualifications and oath of office shall be the same as apply to other county officers. Each county auditor shall, before entering upon the duties of the office, give bond (or, if the county is self-insured, the county through its self-insurance program may provide bonding) in such penalty and with such security as the county board deems sufficient, which bond shall be substantially in the form required by law to be given by the county clerk. Such bond shall be filed with the county clerk on or before the day the county auditor takes office. In case of a vacancy in the office of county auditor caused by death, resignation, or removal from office, the vacancy shall be filled as provided for filling vacancies of other county offices. If the auditor is temporarily unable to perform his or her duties for any reason, the deputy auditor, if there is one, shall assume the duties of the auditor until the auditor is able to resume his or her duties or until a replacement for the auditor is chosen.
55 ILCS 5/3-1001