Mendota is served by U.S interstate 39, U.S. Route 34, U.S. Route 52, and by many state highways including Illinois Route 251. There is also daily train service by Amtrak at the Mendota (Amtrak station) to Chicago and also to points west on the Illinois Zephyr, Carl Sandburg, and Southwest Chief routes.
Helen E. Hokinson, cartoonist for The New Yorker from 1925 until her death in 1949, was born and raised in Mendota. Former Minnesota Vikings runningback Bill Brown was also born and raised in Mendota. Wartburg College (now located in Waverly, Iowa) was located in Mendota from 1875 to 1885.
As of the census of 2000, there were 7,272 people, 2,748 households, and 1,901 families residing in the city. The population density was 1,924.3 people per square mile (742.8/km²). There were 2,939 housing units at an average density of 777.7/sq mi (300.2/km²). The racial makeup of the city was 89.37% White, 0.40% African American, 0.30% Native American, 0.45% Asian, 8.42% from other races, and 1.06% from two or more races. Hispanic or Latino of any race were 18.15% of the population.
There were 2,748 households out of which 32.9% had children under the age of 18 living with them, 55.5% were married couples living together, 9.9% had a female householder with no husband present, and 30.8% were non-families. 27.3% of all households were made up of individuals and 14.7% had someone living alone who was 65 years of age or older. The average household size was 2.56 and the average family size was 3.10.
In the city the population was spread out with 25.6% under the age of 18, 9.4% from 18 to 24, 25.0% from 25 to 44, 21.5% from 45 to 64, and 18.5% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 90.5 males. For every 100 females age 18 and over, there were 87.0 males.
The median income for a household in the city was $39,354, and the median income for a family was $46,279. Males had a median income of $35,344 versus $20,556 for females. The per capita income for the city was $17,731. About 7.6% of families and 11.2% of the population were below the poverty line, including 16.6% of those under age 18 and 4.4% of those age 65 or over.