55 ILCS 120/2

The officer having the custody of such papers, drawings, maps, writings and records shall permit search to be made at all reasonable hours and under his supervision for such as may be deemed of historic interest. Whenever so directed by the county board in the manner prescribed in the foregoing section such officer shall deliver the same to the trustee, directors or librarian or other officer of the Department of Natural Resources or society designated by such county board.