As of the census of 2000, there were 108,724 people, 39,206 households, and 22,778 families residing in the city. The population density was 2,685.8/km² (6,956.3/mi²). There were 40,406 housing units at an average density of 998.1/km² (2,585.2/mi²). The racial makeup of the city was 69.48% White, 1.40% Black or African American, 0.78% Native American, 6.90% Asian, 0.60% Pacific Islander, 16.57% from other races, and 4.27% from two or more races. 31.75% of the population were Hispanic or Latino of any race.
There were 39,206 households out of which 29.2% had children under the age of 18 living with them, 42.8% were married couples living together, 10.3% had a female householder with no husband present, and 41.9% were non-families. 28.1% of all households were made up of individuals and 6.3% had someone living alone who was 65 years of age or older. The average household size was 2.69 and the average family size was 3.34.
In the city the population was spread out with 23.2% under the age of 18, 11.2% from 18 to 24, 39.0% from 25 to 44, 18.1% from 45 to 64, and 8.4% who were 65 years of age or older. The median age was 32 years. For every 100 females there were 105.0 males. For every 100 females age 18 and over, there were 103.9 males.
The median income for a household in the city was $50,732, and the median income for a family was $55,456. Males had a median income of $38,670 versus $32,365 for females. The per capita income for the city was $23,342. About 8.2% of families and 12.6% of the population were below the poverty line, including 16.0% of those under age 18 and 6.2% of those age 65 or over.
Costa Mesa is served by several bus lines of the Orange County Transportation Authority (OCTA), but most transportation is by automobile. Two freeways terminate here, State Route 73 and State Route 55 (also known as the Costa Mesa Freeway). The San Diego Freeway, Interstate 405, also runs through the city.