|Nickname: The Red Bud City|
|Elevation||628 ft (191 m)|
|Area||4.08 sq mi (11 km2)|
|- land||4.08 sq mi (11 km2)|
|- water||0.00 sq mi (0 km2)|
|Density||1,368.0 / sq mi (528 / km2)|
|Founded||February 24, 1853|
|- summer (DST)||CDT (UTC-5)|
|Wikimedia Commons: Auburn, Illinois|
Auburn is located at (39.588969, -89.745962).
According to the 2010 census, the city has a total area of 4.08 square miles (10.6 km2), all land.
As of the census of 2000, there were 4,317 people, 1,618 households, and 1,187 families residing in the city. The population density was 1,368.0 people per square mile (527.5/km²). There were 1,753 housing units at an average density of 555.5 per square mile (214.2/km²). The racial makeup of the city was 98.36% White, 0.30% African American, 0.16% Native American, 0.28% Asian, 0.30% from other races, and 0.60% from two or more races. Hispanic or Latino of any race were 0.76% of the population.
There were 1,618 households out of which 42.0% had children under the age of 18 living with them, 56.6% were married couples living together, 13.2% had a female householder with no husband present, and 26.6% were non-families. 22.9% of all households were made up of individuals and 9.7% had someone living alone who was 65 years of age or older. The average household size was 2.63 and the average family size was 3.09.
In the city the population was spread out with 30.4% under the age of 18, 7.5% from 18 to 24, 33.1% from 25 to 44, 17.5% from 45 to 64, and 11.5% who were 65 years of age or older. The median age was 33 years. For every 100 females there were 88.2 males. For every 100 females age 18 and over, there were 82.4 males.
The median income for a household in the city was $43,250, and the median income for a family was $49,200. Males had a median income of $34,339 versus $24,167 for females. The per capita income for the city was $18,368. About 4.8% of families and 5.5% of the population were below the poverty line, including 8.0% of those under age 18 and 4.5% of those age 65 or over.