Champaign County is part of the Champaign–Urbana Metropolitan Statistical Area.
As of the census of 2000, there were 179,669 people, 70,597 households, and 39,322 families residing in the county. The population density was 180 people per square mile (70/km²). There were 75,280 housing units at an average density of 76 per square mile (29/km²). The racial makeup of the county was 78.78% White, 11.16% Black or African American, 0.24% Native American, 6.45% Asian, 0.04% Pacific Islander, 1.34% from other races, and 1.99% from two or more races. 2.90% of the population were Hispanic or Latino of any race. 23.9% were of German, 9.6% Irish, 8.9% English and 7.4% American ancestry according to Census 2000. 88.7% spoke English, 2.9% Spanish, 1.7% Chinese or Mandarin and 1.3% Korean as their first language.
There were 70,597 households out of which 27.20% had children under the age of 18 living with them, 43.60% were married couples living together, 9.20% had a female householder with no husband present, and 44.30% were non-families. 31.40% of all households were made up of individuals and 7.80% had someone living alone who was 65 years of age or older. The average household size was 2.33 and the average family size was 2.96.
In the county the population was spread out with 21.00% under the age of 18, 23.10% from 18 to 24, 28.20% from 25 to 44, 18.00% from 45 to 64, and 9.70% who were 65 years of age or older. The median age was 29 years. For every 100 females there were 101.10 males. For every 100 females age 18 and over, there were 99.70 males.
The median income for a household in the county was $37,780, and the median income for a family was $52,591. Males had a median income of $36,844 versus $26,421 for females. The per capita income for the county was $19,708. About 6.90% of families and 16.10% of the population were below the poverty line, including 11.80% of those under age 18 and 4.90% of those age 65 or over.