Rio is a village in Knox County, Illinois, United States. The population was 220 at the 2010 census. It is part of the Galesburg Micropolitan Statistical Area.
Rio is in the northwest corner of Knox County, 13 miles (21 km) north of Galesburg, the county seat. The village, like its other rural neighbors, has rich soil ideal for farming corn and soybeans. A few very small creeks run through its outskirts. None of them are formally named. There are a few small hills that coast under the streets of the village, and there are a few sizable dropoffs throughout the land that almost look like shallow or gradual cliffs as some of the local agricultural fields are rolling and steep. The land drains to North Henderson Creek, a west-flowing stream which runs via Henderson Creek to the Mississippi River near Oquawka.
According to the 2010 census, Rio has a total area of 0.27 square miles (0.70 km), all land.
As of the census of 2000, there were 240 people, 94 households, and 72 families residing in the village. The population density was 737.6 people per square mile (280.8/km²). There were 101 housing units at an average density of 310.4 per square mile (118.2/km²). The racial makeup of the village was 99.58% White, 0.42% from other races. Hispanic or Latino of any race were 2.08% of the population.
There were 94 households out of which 35.1% had children under the age of 18 living with them, 70.2% were married couples living together, 5.3% had a female householder with no husband present, and 23.4% were non-families. 20.2% of all households were made up of individuals and 8.5% had someone living alone who was 65 years of age or older. The average household size was 2.55 and the average family size was 2.92.
In the village, the population was spread out with 24.2% under the age of 18, 4.2% from 18 to 24, 32.1% from 25 to 44, 22.1% from 45 to 64, and 17.5% who were 65 years of age or older. The median age was 38 years. For every 100 females, there were 101.7 males. For every 100 females age 18 and over, there were 102.2 males.
The median income for a household in the village was $37,750, and the median income for a family was $40,750. Males had a median income of $35,625 versus $21,250 for females. The per capita income for the village was $17,181. None of the families and 2.0% of the population were living below the poverty line.