55 ILCS 5/1-3010
The commissioner shall note, at the end of each paper he shall transcribe, the book and page from which the same was transcribed, and shall make a correct double index of the records; and on the completion of his duties, the commissioner shall return the books to the recorder of the new county, with his certificate attached thereto, showing that he has complied with the law; whereupon they shall be taken and considered, to all intents and purposes, as books of records of deeds, mortgages and title papers for the new county. And copies of the record, certified by the officer having the custody of the same, shall be evidence in all courts and places, in the same manner that copies of records are evidence in other cases, and with like effect.
55 ILCS 5/1-3010