LaSalle County is located in the North Central region of the U.S. state of Illinois; it has an estimated population of 111,241 as of 2014 and its county seat and largest city is Ottawa.
According to the U.S. Census Bureau, the county has a total area of 1,148 square miles (2,970 km), of which 1,135 square miles (2,940 km) is land and 13 square miles (34 km) (1.1%) is water. It is the second-largest county in Illinois by land area and the fourth-largest by total area.
As of the 2010 United States Census, there were 113,924 people, 45,347 households, and 30,116 families residing in the county. The population density was 100.4 inhabitants per square mile (38.8/km). There were 49,978 housing units at an average density of 44.0 per square mile (17.0/km). The racial makeup of the county was 93.2% white, 1.9% black or African American, 0.7% Asian, 0.3% American Indian, 2.5% from other races, and 1.4% from two or more races. Those of Hispanic or Latino origin made up 8.0% of the population. In terms of ancestry, 33.7% were German, 19.0% were Irish, 9.8% were English, 9.2% were Italian, 7.8% were Polish, 6.0% were American, and 5.5% were Norwegian.
Of the 45,347 households, 30.3% had children under the age of 18 living with them, 50.9% were married couples living together, 10.5% had a female householder with no husband present, 33.6% were non-families, and 28.6% of all households were made up of individuals. The average household size was 2.45 and the average family size was 3.00. The median age was 41.0 years.
The median income for a household in the county was $51,705 and the median income for a family was $62,252. Males had a median income of $49,551 versus $30,207 for females. The per capita income for the county was $24,982. About 8.0% of families and 10.8% of the population were below the poverty line, including 15.3% of those under age 18 and 6.8% of those age 65 or over.