5 ILCS 465/2

The commissioners or trustees of all penal and reformatory, State educational and State charitable institutions of this State shall provide United States national flags of not less than ten by twenty feet in size and cause the same to be unfurled and kept floating above the said penal and reformatory, State educational and State charitable institutions or on a suitable flag pole from eight o'clock a.m. to five o'clock p.m. on each and every legal holiday in the year and on such other days as the commissioners or trustees may determine.