Geography
Carbondale is located at 37°43′35″N, 89°13′13″W (37.726418, -89.220270) It is in the watershed of the Big Muddy River, at 415 feet above sea level.
 
According to the United States Census Bureau, the city has a total area of 12.1 square miles (31.4 km²), of which, 11.9 square miles (30.8 km²) of it is land and 0.2 square miles (0.6 km²) of it is water. The total area is 2.06% water. 
 
Demographics
As of the census of 2000 , there are 25,597 people, 10,018 households, and 3,493 families residing in the city. The population density is 2,152.0 people per square mile (830.9/km²). There are 11,005 housing units at an average density of 925.2/sq mi (357.2/km²). The racial makeup of the city is 66.08% White, 23.14% Black or African American, 0.22% Native American, 6.67% Asian, 0.08% Pacific Islander, 1.42% from other races, and 2.40% from two or more races. 3.05% of the population are Hispanic or Latino of any race. [Race, household, age, and income data does not include corrections introduced through Count Question Review updates that added 4,916 population and 37 households to the official 2000 population count for Carbondale city.]
 There are 9,981 households out of which 17.0% have children under the age of 18 living with them, 22.1% are married couples living together, 10.1% have a female householder with no husband present, and 21.5% are non-families. 43.5% of all households are made up of individuals and 6.9% have someone living alone who is 65 years of age or older. The average household size is 2.33 and the average family size is 2.78.
 The age distribution, which is heavily influenced by the presence of SIU, is: 15.8% under the age of 18, 35.4% from 18 to 24, 27.1% from 25 to 44, 12.5% from 45 to 64, and 9.3% who are 65 years of age or older. The median age is 25 years, which is also fairly typical for a university town. For every 100 females there are 106.2 males. For every 100 females age 18 and over, there are 105.6 males.
 The median income for a household in the city is $15,882, and the median income for a family is $34,601. Males have a median income of $30,217 versus $24,114 for females. The per capita income for the city is $13,346. 41.4% of the population and 23.5% of families are below the poverty line. Out of the total population, 32.1% of those under the age of 18 and 13.2% of those 65 and older are living below the poverty line. However, traditional measures of poverty can be misleading when applied to a community with a large proportion of students, such as Carbondale.