55 ILCS 5/6-28001

County highway working cash fund in counties of 500,000 or more. In each county in this State having a population of 500,000 or more inhabitants a fund to be known as a county highway working cash fund may be created, set apart, maintained and administered in the manner prescribed in this Division for the purpose of enabling such county to have in its treasury at all times sufficient money to meet demands thereon for ordinary and necessary expenditures for county highway purposes.