Bureau County is a county located in the U.S. state of Illinois. As of the 2010 United States Census, the population was 34,978. Its county seat is Princeton.
According to the US Census Bureau, the county has a total area of 874 square miles (2,260 km), of which 869 square miles (2,250 km) is land and 4.5 square miles (12 km) (0.5%) is water. Big Bureau Creek is the main body of water.
As of the 2010 United States Census, there were 34,978 people, 14,262 households, and 9,605 families residing in the county. The population density was 40.2 inhabitants per square mile (15.5/km). There were 15,720 housing units at an average density of 18.1 per square mile (7.0/km). The racial makeup of the county was 94.2% white, 0.7% Asian, 0.6% black or African American, 0.3% American Indian, 3.0% from other races, and 1.3% from two or more races. Those of Hispanic or Latino origin made up 7.7% of the population. In terms of ancestry, 32.8% were German, 13.8% were Irish, 12.1% were English, 9.2% were American, 8.8% were Italian, 7.6% were Swedish, and 5.8% were Polish.
Of the 14,262 households, 29.8% had children under the age of 18 living with them, 53.6% were married couples living together, 9.2% had a female householder with no husband present, 32.7% were non-families, and 28.0% of all households were made up of individuals. The average household size was 2.42 and the average family size was 2.94. The median age was 42.5 years.
The median income for a household in the county was $45,692 and the median income for a family was $55,217. Males had a median income of $42,327 versus $29,210 for females. The per capita income for the county was $24,103. About 8.6% of families and 11.1% of the population were below the poverty line, including 15.3% of those under age 18 and 7.5% of those age 65 or over.