As of the census of 2006, there were 9752 people, 1,825 households, and 1,545 families residing in the city. The population density was 4,229.4 people per square mile (1,629.1/km²). There were 1,878 housing units at an average density of 1,006.7/sq mi (387.8/km²). The racial makeup of the city was 27.33% White, 0.66% Black or African American, 1.31% Native American, 0.72% Asian, 0.16% Pacific Islander, 63.12% from other races, and 6.70% from two or more races. 94.65% of the population were Hispanic or Latino of any race.
There were 1,825 households out of which 53.4% had children under the age of 18 living with them, 56.8% were married couples living together, 16.9% had a female householder with no husband present, and 15.3% were non-families. 9.1% of all households were made up of individuals and 3.9% had someone living alone who was 65 years of age or older. The average household size was 4.32 and the average family size was 4.38.
In the city the population was spread out with 33.9% under the age of 18, 15.3% from 18 to 24, 30.9% from 25 to 44, 14.7% from 45 to 64, and 5.2% who were 65 years of age or older. The median age was 25 years. For every 100 females there were 130.2 males. For every 100 females age 18 and over, there were 142.0 males.
The median income for a household in the city was $23,705, and the median income for a family was $22,984. Males had a median income of $17,500 versus $21,319 for females. The per capita income for the city was $6,967. About 35.2% of families and 41.9% of the population were below the poverty line, including 49.4% of those under age 18 and 16.6% of those age 65 or over.
As of 2000, about 44.1% of employed Mendota civilians over age 16 were employed in agriculture, forestry, fishing, or hunting. 14.1% were employed in the second-largest sector for this group, wholesale trade.