As of the 2000 census, the city had a total population of 106,221.
Joliet was a significant transportation center on the Illinois and Michigan Canal. It was the crossroads of two important highways of the 20th Century, the storied Route 66 (decomissioned in 1985) and the historically significant Lincoln Highway, later known as U.S. 30. It was the home to Joliet Prison and Joliet Arsenal, both now closed. Statesville Correctional Center remains open. Joliet has recently become something of an anchor city in the Chicagoland area.
According to the United States Census Bureau, the city has a total area of 99.3 km² (38.3 mi²). 98.6 km² (38.1 mi²) of it is land and 0.8 km² (0.3 mi²) of it is water. The total area is 0.76% water.
As of the census of 2000, there are 106,221 people, 36,182 households, and 25,399 families residing in the city. The population density is 1,077.6/km² (2,790.9/mi²). There are 38,176 housing units at an average density of 387.3/km² (1,003.1/mi²). The racial makeup of the city is 69.32% White, 18.16% African American, 0.28% Native American, 1.14% Asian, 0.02% Pacific Islander, 8.97% from other races, and 2.09% from two or more races. 18.41% of the population are Hispanic or Latino of any race.
There are 36,182 households out of which 38.8% have children under the age of 18 living with them, 51.9% are married couples living together, 13.3% have a female householder with no husband present, and 29.8% are non-families. 24.7% of all households are made up of individuals and 10.0% have someone living alone who is 65 years of age or older. The average household size is 2.81 and the average family size is 3.39.
In the city the population is spread out with 29.5% under the age of 18, 10.1% from 18 to 24, 33.1% from 25 to 44, 16.3% from 45 to 64, and 11.0% who are 65 years of age or older. The median age is 31 years. For every 100 females there are 98.2 males. For every 100 females age 18 and over, there are 95.3 males.
The median income for a household in the city is $47,761, and the median income for a family is $55,870. Males have a median income of $41,909 versus $29,100 for females. The per capita income for the city is $19,390. 10.8% of the population and 7.7% of families are below the poverty line. Out of the total people living in poverty, 13.5% are under the age of 18 and 8.2% are 65 or older.