Southglenn is a former census-designated place (CDP) in Arapahoe County, Colorado, United States. The population was 43,520 at the 2000 census. It has been a part of the city of Centennial since the city's incorporation in 2001.
According to the United States Census Bureau, the CDP had a total area of 9.7 square miles (25 km2), all land.
As of the census of 2000, there were 43,520 people, 16,436 households, and 12,359 families residing in the CDP. The population density was 4,467.4 per square mile (1,725.2/km²). There were 16,694 housing units at an average density of 1,713.7 per square mile (661.8/km²). The racial makeup of the CDP was 94.60% White, 0.79% African American, 0.40% Native American, 1.83% Asian, 0.06% Pacific Islander, 0.86% from other races, and 1.45% from two or more races. Hispanic or Latino of any race were 4.04% of the population.
There were 16,436 households out of which 35.3% had children under the age of 18 living with them, 63.6% were married couples living together, 8.7% had a female householder with no husband present, and 24.8% were non-families. 20.1% of all households were made up of individuals and 6.4% had someone living alone who was 65 years of age or older. The average household size was 2.62 and the average family size was 3.03.
In the CDP the population was spread out with 26.1% under the age of 18, 5.6% from 18 to 24, 26.7% from 25 to 44, 29.4% from 45 to 64, and 12.2% who were 65 years of age or older. The median age was 41 years. For every 100 females there were 93.4 males. For every 100 females age 18 and over, there were 89.1 males.
The median income for a household in the CDP was $69,833, and the median income for a family was $77,405. Males had a median income of $53,282 versus $35,754 for females. The per capita income for the CDP was $32,699. About 1.4% of families and 2.6% of the population were below the poverty line, including 2.7% of those under age 18 and 2.8% of those age 65 or over.
See also 
- Outline of Colorado
- State of Colorado
- Colorado cities and towns
- Colorado counties
- Colorado metropolitan areas
- "American FactFinder". United States Census Bureau. Retrieved 2008-01-31.
- "US Gazetteer files: 2010, 2000, and 1990". United States Census Bureau. 2011-02-12. Retrieved 2011-04-23.
- "CENSUS OF POPULATION AND HOUSING (1790-2000)". U.S. Census Bureau. Retrieved 2010-07-17.
- Returned as "Littleton Southeast" in 1970