The Cook County Treasurer is a constitutional office in Illinois, manages the second largest property tax collection system in the United States of America.  The Cook County Treasurer's Office is chiefly responsible for mailing tax bills and accurately collecting, investing, distributing and issuing refunds on approximately $10 billion in real-estate tax payments annually.  These billings and collection involve the owners and owners representatives for nearly 1.7 million local government agencies and sub agencies across Cook County.