Livingston County is a county in the US state of Illinois. In the 2000 census the county had a population of 39,678 inhabitants. It is part of Pontiac's micropolitan area. The county seat is Pontiac. The county was formed on February 27,1837 from portions of Iroquois, LaSalle and McLean counties. It was named in honor of Edward Livingston, a statesman from New York.