As of the census of 2000, there were 26,232 people, 9,276 households, and 6,205 families residing in the city. The population density was 2,360.6 people per square mile (911.6/km²). There were 9,686 housing units at an average density of 871.6/sq mi (336.6/km²). The racial makeup of the city was 75.44% White, 0.73% African American, 1.02% Native American, 2.58% Asian, 0.15% Pacific Islander, 17.13% from other races, and 2.95% from two or more races. Hispanic or Latino of any race were 25.12% of the population.
There were 9,276 households out of which 36.5% had children under the age of 18 living with them, 51.3% were married couples living together, 11.4% had a female householder with no husband present, and 33.1% were non-families. 26.1% of all households were made up of individuals and 10.9% had someone living alone who was 65 years of age or older. The average household size was 2.75 and the average family size was 3.32.
In the city the population was spread out with 29.0% under the age of 18, 11.9% from 18 to 24, 29.0% from 25 to 44, 17.6% from 45 to 64, and 12.5% who were 65 years of age or older. The median age was 31 years. For every 100 females there were 96.2 males. For every 100 females age 18 and over, there were 92.9 males.
The median income for a household in the city was $53,496. Males had a median income of $33,724 versus $27,244 for females. The per capita income for the city was $17,041. About 10.8% of families and 15.9% of the population were below the poverty line, including 18.9% of those under age 18 and 7.1% of those age 65 or over.
The new Skagit Station, built in 2004, delivers true multimodal transportation to a rapidly growing region. Commuters and travelers can switch between modes of transportation in downtown Mount Vernon. The station offers stops for the Skagit Transit bus, Greyhound bus, Amtrak Cascades rail and local taxi. The new Everett Express bus route connects to the Sounder Train in Everett.
Skagit Regional Airport, five miles (8 km) northwest, fills much of the area's general aviation needs. The closest commercial airport with scheduled passenger service is Bellingham International Airport, 25 miles (40 km) north.