|• Village President||Michael Tilstra|
|• Total||1.33 sq mi (3.4 km2)|
|• Land||1.33 sq mi (3.4 km2)|
|• Water||0.00 sq mi (0.0 km2)|
|Elevation||669 ft (204 m)|
|GNIS feature ID||0415120|
Onarga has a continental climate, with four distinct seasons. Onarga experiences cold winters, with frequent snowfall and temperatures that sometimes plunge to -20°F or colder. Average January high temperatures are generally in the 20s. Record amounts of snowfall for the area were measured in the Winter of 2007-08. Spring is mild, and often rainy, windy, and cloudy with high temperatures ranging from the 50s to 80s. Summers are hot and humid, generally with brief periods of intense thunderstorm and rainfall. Average summer highs are usually in the mid 80s. Falls are crisp and drier, and first killing frosts generally come in October. Onarga's typical summer weather is highly conducive to growing corn and soybeans, which dominate the rural landscape. On average, 40 inches of precipitation per year fall at Onarga.
Onarga has a rich and celebrated history for a small town. It was originally laid out in the mid-19th century alongside the development of the railroad from Chicago. Because of its close proximity to Spring Creek, Onarga was one of the first settled areas of Iroquois County. The town grew rapidly but the population began to level off by the mid-20th century and now maintains fairly minimal population growth. Onarga is often associated with its tree and shrub nurseries that have been in business for over 100 years, earning Onarga the nickname, "The Nursery Capital of the Midwest." Many fields surrounding the town bear rows of trees and bushes rather than corn and soybeans, which are otherwise ubiquitous throughout the region. The prosperous nursery businesses have led to a great amount of ethnic diversity in Onarga, as many Mexican and Mexican-American migrant workers have chosen to maintain roots in the community.
Onarga celebrated its sesquicentennial with a nearly week-long festival in the summer of 2004, which included social events and a strong focus on the history of the community.
Onarga has a golf course, several restaurants, and Lake Arrowhead.
As of the census of 2000, there were 1,438 people, 475 households, and 342 families residing in the village. The population density was 1,097.9 people per square mile (423.8/km²). There were 525 housing units at an average density of 400.8 per square mile (154.7/km²). The racial makeup of the village was 71.21% White, 2.23% African American, 0.35% Native American, 0.21% Asian, 24.41% from other races, and 1.60% from two or more races. Hispanic or Latino of any race were 35.26% of the population.
There were 475 households out of which 40.2% had children under the age of 18 living with them, 56.2% were married couples living together, 10.7% had a female householder with no husband present, and 27.8% were non-families. 24.8% of all households were made up of individuals and 15.2% had someone living alone who was 65 years of age or older. The average household size was 2.87 and the average family size was 3.42.
In the village the population was spread out with 33.1% under the age of 18, 10.4% from 18 to 24, 25.9% from 25 to 44, 18.8% from 45 to 64, and 11.8% who were 65 years of age or older. The median age was 30 years. For every 100 females there were 109.6 males. For every 100 females age 18 and over, there were 93.6 males.
The median income for a household in the village was $35,852, and the median income for a family was $46,016. Males had a median income of $31,146 versus $19,732 for females. The per capita income for the village was $13,623. About 8.0% of families and 10.9% of the population were below the poverty line, including 17.1% of those under age 18 and 5.0% of those age 65 or over.
- "Onarga". Geographic Names Information System, U.S. Geological Survey. Retrieved 2010-10-15.
- "US Gazetteer files: 2010, 2000, and 1990". United States Census Bureau. 2011-02-12. Retrieved 2011-04-23.
- "2010 Census U.S. Gazetteer Files for Places – Illinois". United States Census. Retrieved 2012-10-13.
- "American FactFinder". United States Census Bureau. Retrieved 2008-01-31.