With an estimated 5,287,037 residents, Cook County is the most populous county in the State of Illinois and the second most populous county in the United States, coming only after Los Angeles County in California.[1] The County is 946 square miles in size – of that only 15% is unincorporated by the City of Chicago or other municipalities. The role of Cook County government is to provide healthcare, court, and public safety services, as well as administer vital records and assess and collect property taxes.