Henry is named after General James D. Henry, and was initially surveyed in 1834. The topography of the land on the west side of the Illinois River, with relatively steep banks rising well above river level, assured early settlers that their homes would not flood. Its slogan, "Best Town in Illinois by a Dam Site," is derived from the city's distinction of having the first lock and dam built on the Illinois River. It was completed in 1870 at a cost of $400,000. The retreat house of the Roman Catholic Diocese of Peoria, Illinois is located here.
Geography
Henry is located at . According to the 2010 census, Henry has a total area of, of which is land and is water.
Geomorphology and geology
Henry lies on a segment of a river terrace that is about long just over wide. This fluvial terrace is underlain by stratified; yellowish brown to grayish brown; calcareous; and usually clean and moderately well sortedsand and gravel with cobbles and boulders. These sands and gravels contain occasional beds of silt and clay and unconformably overlies older sand and gravel deposits, glacial till, or bedrock. The sands and gravels underlying the terrace on which Henry lies were deposited by the Kankakee Torrent about 19,000 BP calibratedyears ago. Within the Illinois River valley, these sediments typically range thick. These and other Wisconsinan coarse-grained, fluvial sands and gravel within Illinois have been named after Henry, Illinois as and are currently known as the Henry Formation, a geological formation. The parts of the Henry Formation, which of either fluvial, glaciofluvial origin, are designated as the Mackinaw facies of the Henry Formation. The original exposure from which the Henry Formation was named was a former sand and gravel pit that once was located along Illinois Highway 29, north of Henry
Demographics
As of the census of 2000, there were 2,540 people, 1,014 households, and 678 families residing in the city. The population density was 1,821.3 people per square mile. There were 1,085 housing units at an average density of 778.0 per square mile. The racial makeup of the city was 97.68% White, 0.51% African American, 0.20% Native American, 0.20% Asian, 0.12% from other races, and 1.30% from two or more races. Hispanic or Latino of any race were 0.63% of the population. There were 1,014 households out of which 29.6% had children under the age of 18 living with them, 55.2% were married couplesliving together, 8.2% had a female householder with no husband present, and 33.1% were non-families. 29.8% of all households were made up of individuals and 16.9% had someone living alone who was 65 years of age or older. The average household size was 2.42 and the average family size was 3.00. In the city the population was spread out with 23.9% under the age of 18, 6.9% from 18 to 24, 24.1% from 25 to 44, 23.0% from 45 to 64, and 22.1% who were 65 years of age or older. The median age was 42 years. For every 100 females, there were 88.1 males. For every 100 females age 18 and over, there were 87.1 males. The median income for a household in the city was $40,236, and the median income for a family was $50,375. Males had a median income of $39,919 versus $18,621 for females. The per capita income for the city was $18,473. About 5.7% of families and 5.6% of the population were below the poverty line, including 5.5% of those under age 18 and 6.3% of those age 65 or over.
Education
Henry has its own school district, Henry-Senachwine Consolidated Unit School District #5, that includes two schools.
The two schools that make up CUSD #5 each have their own mascots: cardinals for the grade/junior high school and mallards for the high school. Both schools use red as the primary school color.
