McLean County is the largest county by land area in the U.S. state of Illinois. According to the 2010 census, it had a population of 169,572. Its county seat is Bloomington.
According to the U.S. Census Bureau, the county has a total area of 1,186 square miles (3,070 km), of which 1,183 square miles (3,060 km) is land and 2.9 square miles (7.5 km) (0.2%) is water. It is the largest county in Illinois by land area and third-largest by total area. McLean County is actually larger than the land area of Rhode Island (1045 sq mi).
As of the 2010 United States Census, there were 169,572 people, 65,104 households, and 40,124 families residing in the county. The population density was 143.3 inhabitants per square mile (55.3/km). There were 69,656 housing units at an average density of 58.9 per square mile (22.7/km). The racial makeup of the county was 84.3% white, 7.3% black or African American, 4.3% Asian, 0.2% American Indian, 1.5% from other races, and 2.3% from two or more races. Those of Hispanic or Latino origin made up 4.4% of the population. In terms of ancestry, 31.2% were German, 15.4% were Irish, 11.4% were American, and 11.0% were English.
Of the 65,104 households, 31.4% had children under the age of 18 living with them, 48.5% were married couples living together, 9.6% had a female householder with no husband present, 38.4% were non-families, and 28.1% of all households were made up of individuals. The average household size was 2.44 and the average family size was 3.02. The median age was 32.1 years.
The median income for a household in the county was $57,642 and the median income for a family was $77,093. Males had a median income of $52,271 versus $39,685 for females. The per capita income for the county was $28,167. About 6.2% of families and 12.9% of the population were below the poverty line, including 11.4% of those under age 18 and 5.5% of those age 65 or over.