The office of the election commissioner or county clerk shall remain open during the usual business days of the year for purposes of general registration and revision and for the transaction of the business of the office. Such registration and revision shall be carried on at all times during the regular business hours of the office of the election commissioner or county clerk ending at 6 p.m. on the second Friday preceding any election. The election commissioner or county clerk may, during any of the seven days immediately preceding the deadline for registration, cause his or her office to be open at times in addition to the hours during which it is required by law to be open in order for electors to register to vote. The office of the election commissioner or county clerk shall be a designated voter registration agency for purposes of section 7 of the National Voter Registration Act of 1993, 42 U.S.C. 1973gg-5, as such section existed on March 11, 2008.