Littleton became widely known in 1999 when the Columbine High School massacre occurred at nearby Columbine High School, which some in the news media erroneously reported as being located in the city. The school is actually in unincorporated Jefferson County, yet in a ZIP code associated primarily with Littleton (see Neighboring Communities... below). The school is one of the schools of the Jefferson County school system and not one of the Littleton Public Schools.
The Colorado Center for the Blind, a skills training program for blind teenagers and adults operated by the National Federation of the Blind, is located in Littleton. The Denver Theological Seminary is also in Littleton.
Intelligent Vehicle Safety Technologies' "Desert Tortoise," a competitor in the DARPA Grand Challenge, is based in Littleton.
The city is also the site of the grave of Alferd Packer, an American prospector. He is one of three people imprisoned in the United States for cannibalism.
Littleton is the home town of famed Hispanic business men, brothers, Sam J. Chavez, Jr. and Lloyd G. Chavez, Sr.
As of the census of 2000, there were 40,340 people, 17,313 households, and 10,387 families residing in the city. The population density was 2,984.8 people per square mile (1,152.0/km²). There were 18,084 housing units at an average density of 1,338.0/sq mi (516.4/km²). The racial makeup of the city was 91.77% White, 1.16% African American, 0.73% Native American, 1.66% Asian, 0.06% Pacific Islander, 2.67% from other races, and 1.95% from two or more races. Hispanic or Latino of any race were 8.45% of the population.
There were 17,313 households out of which 28.0% had children under the age of 18 living with them, 47.3% were married couples living together, 9.2% had a female householder with no husband present, and 40.0% were non-families. 33.3% of all households were made up of individuals and 11.1% had someone living alone who was 65 years of age or older. The average household size was 2.29 and the average family size was 2.96.
In the city the population was spread out with 23.3% under the age of 18, 8.2% from 18 to 24, 30.1% from 25 to 44, 24.2% from 45 to 64, and 14.2% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 94.5 males. For every 100 females age 18 and over, there were 91.0 males.
The median income for a household in the city was $50,583, and the median income for a family was $64,671. Males had a median income of $43,698 versus $33,377 for females. The per capita income for the city was $28,681. About 3.9% of families and 6.0% of the population were below the poverty line, including 7.5% of those under age 18 and 5.1% of those age 65 or over.