Lebanon is home to McKendree College, the oldest college in Illinois.
As of the census of 2000, there are 3,523 people, 1,275 households, and 804 families residing in the city. The population density is 632.7/km² (1,641.4/mi²). There are 1,389 housing units at an average density of 249.4/km² (647.2/mi²). The racial makeup of the city is 78.46% White, 18.45% African American, 0.34% Native American, 0.48% Asian, 0.09% Pacific Islander, 0.40% from other races, and 1.79% from two or more races. 1.53% of the population are Hispanic or Latino of any race.
There are 1,275 households out of which 28.8% have children under the age of 18 living with them, 48.2% are married couples living together, 11.5% have a female householder with no husband present, and 36.9% are non-families. 28.5% of all households are made up of individuals and 12.9% have someone living alone who is 65 years of age or older. The average household size is 2.41 and the average family size is 2.98.
In the city the population is spread out with 20.8% under the age of 18, 18.6% from 18 to 24, 22.9% from 25 to 44, 21.0% from 45 to 64, and 16.7% who are 65 years of age or older. The median age is 36 years. For every 100 females there are 84.7 males. For every 100 females age 18 and over, there are 80.8 males.
The median income for a household in the city is $37,042, and the median income for a family is $48,711. Males have a median income of $30,597 versus $21,341 for females. The per capita income for the city is $17,125. 13.4% of the population and 9.8% of families are below the poverty line. Out of the total people living in poverty, 14.2% are under the age of 18 and 7.1% are 65 or older.