Jefferson County Illinois

Jefferson County Sheriff, Illinois
Jefferson County Illinois

Jefferson County is a county located in the state of Illinois. As of 2000, the population is 40,045. Its county seat is Mt. Vernon6.


According to the U.S. Census Bureau, the county has a total area of 1,512 km² (584 mi²). 1,479 km² (571 mi²) of it is land and 33 km² (13 mi²) of it is water. The total area is 2.19% water.


As of the census2 of 2000, there are 40,045 people, 15,374 households, and 10,561 families residing in the county. The population density is 27/km² (70/mi²). There are 16,990 housing units at an average density of 11/km² (30/mi²). The racial makeup of the county is 89.87% White, 7.83% Black or African American, 0.21% Native American, 0.47% Asian, 0.01% Pacific Islander, 0.45% from other races, and 1.16% from two or more races. 1.33% of the population are Hispanic or Latino of any race.

There are 15,374 households out of which 31.10% have children under the age of 18 living with them, 55.30% are married couples living together, 9.90% have a female householder with no husband present, and 31.30% are non-families. 27.60% of all households are made up of individuals and 13.00% have someone living alone who is 65 years of age or older. The average household size is 2.44 and the average family size is 2.96.

In the county the population is spread out with 24.20% under the age of 18, 8.80% from 18 to 24, 28.40% from 25 to 44, 23.30% from 45 to 64, and 15.30% who are 65 years of age or older. The median age is 38 years. For every 100 females there are 104.10 males. For every 100 females age 18 and over, there are 104.10 males.

The median income for a household in the county is $33,555, and the median income for a family is $41,141. Males have a median income of $34,089 versus $21,015 for females. The per capita income for the county is $16,644. 12.30% of the population and 9.10% of families are below the poverty line. Out of the total population, 14.00% of those under the age of 18 and 11.80% of those 65 and older are living below the poverty line.

Cities and towns