|Area||1.4 sq mi (4 km2)|
|- land||1.4 sq mi (4 km2)|
|Density||505.5 /sq mi (195 /km2)|
|- summer (DST)||CDT (UTC-5)|
Location of Tonica within Illinois
|Wikimedia Commons: Tonica, Illinois|
Tonica is mainly farmland, with a few businesses. It has its own grade school, Tonica Grade School (K-8), with approximately 194 students enrolled.
Tonica is located at (41.215902, -89.067981).
As of the census of 2000, there were 685 people, 292 households, and 193 families residing in the village. The population density was 505.5 people per square mile (194.5/km²). There were 306 housing units at an average density of 225.8/sq mi (86.9/km²). The racial makeup of the village was 98.39% White, 0.29% Native American, 0.15% Asian, 0.44% Pacific Islander, and 0.73% from two or more races. Hispanic or Latino of any race were 4.09% of the population.
There were 292 households out of which 26.7% had children under the age of 18 living with them, 54.5% were married couples living together, 6.8% had a female householder with no husband present, and 33.6% were non-families. 30.8% of all households were made up of individuals and 20.9% had someone living alone who was 65 years of age or older. The average household size was 2.35 and the average family size was 2.91.
In the village the population was spread out with 22.8% under the age of 18, 8.0% from 18 to 24, 24.8% from 25 to 44, 20.4% from 45 to 64, and 23.9% who were 65 years of age or older. The median age was 41 years. For every 100 females there were 95.7 males. For every 100 females age 18 and over, there were 92.4 males.
The median income for a household in the village was $38,333, and the median income for a family was $46,111. Males had a median income of $40,313 versus $20,833 for females. The per capita income for the village was $22,484. About 4.0% of families and 5.3% of the population were below the poverty line, including 8.0% of those under age 18 and 6.4% of those age 65 or over.