As of the census of 2000, there were 24,292 people, 10,477 households, and 6,003 families residing in the city. The population density was 2,726.5/km² (7,064.4/mi²). There were 10,850 housing units at an average density of 1,217.8/km² (3,155.3/mi²). The racial makeup of the city was 60.32% White, 3.04% African American, 0.34% Native American, 26.58% Asian, 0.08% Pacific Islander, 5.17% from other races, and 4.47% from two or more races (perhaps explaining why these percentages sum to about 116%). Hispanic or Latino of any race were 16.07% of the population.
There were 10,477 households out of which 29.4% had children under the age of 18 living with them, 42.4% were married couples living together, 11.4% had a female householder with no husband present, and 42.7% were non-families. 34.9% of all households were made up of individuals and 7.4% had someone living alone who was 65 years of age or older. The average household size was 2.30 and the average family size was 3.05.
In the city the population was spread out with 22.6% under the age of 18, 6.8% from 18 to 24, 34.7% from 25 to 44, 24.5% from 45 to 64, and 11.4% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 86.6 males. For every 100 females age 18 and over, there were 83.3 males.
The median income for a household in the city was $55,728, and the median income for a family was $72,039 (these figures had risen to $76,438 and $96,255 respectively as of a 2007 estimate). Males had a median income of $55,336 versus $40,304 for females. The per capita income for the city was $32,620. About 3.6% of families and 6.1% of the population were below the poverty line, including 5.1% of those under age 18 and 5.7% of those age 65 or over
Fair Oaks Avenue, Huntington Drive, and Mission Street are the main thoroughfares through South Pasadena.
The Pasadena Freeway has two exits in South Pasadena--Orange Grove Avenue and Fair Oaks Avenue.
LACMTA operates six bus lines (79, 176, 256, 260, 485, 762) through South Pasadena. The Metro Gold Line Mission Station is in the heart of South Pasadena, located at the corner of Mission and Meridian.
South Pasadena operates their own public transportation system. Since 2003, South Pasadena has been operating the City of South Pasadena Community Transit to connect with the Mission Gold Line Station, it schedule is linked to the Gold Line schedule. The system was originally called "South Pasadena Gold Link." Additionally South Pasadena has a transit shuttle that operates around the city.
As of 2007, many old and outdated traffic signals are in the process of being replaced throughout South Pasadena.
South Pasadena is known throughout the greater Los Angeles area for its opposition to the extension of the Long Beach Freeway (I-710) from Alhambra's Valley Blvd. to the Foothill Freeway (I-210) in Pasadena at California Blvd. For many years no politician could get elected in South Pasadena, unless they opposed the 710.
Litigation over the 710 extension has run for about three decades. Caltrans (the California Department of Transportation) is now exploring a compromise route of boring a tunnel beneath the city. Having purchased hundreds of properties along the proposed right-of-way in the 1960s, Caltrans proposed selling these in order to partially finance the tunnel. The Southern California real estate boom of the early 2000s caused those properties in South Pasadena alone to appreciate to a combined value of over $300 million.