|City of Oglesby|
Water tower near I-39 in Oglesby
|Elevation||628 ft (191.4 m)|
|Area||4.11 sq mi (10.6 km2)|
|- land||4.11 sq mi (11 km2)|
|- water||0.00 sq mi (0 km2), 0%|
|Density||911.6 / sq mi (352 / km2)|
|Government||City commission government|
|- summer (DST)||CDT (UTC-5)|
Oglesby Lincoln, Oglesby Washington, Holy Family, and Illinois Valley Community College are located in Oglesby.
Oglesby is located at (41.296762, -89.066074).
According to the 2010 census, the city has a total area of 4.11 square miles (10.6 km2), all land.
Natural resources 
Oglesby is located near the confluence of the Illinois River and the north-flowing Vermilion River. It was originally called Portland, due to the cement mined and manufactured in the area that was similar to Portland Cement from England. It was renamed[when?] in honor of Richard Oglesby, a former Governor of Illinois.
The surface ground layers around Oglesby has excellent exposed limestone and coal, as well as riverine transport. It soon became an important center for cement manufacture. Before open-pit mining there were several subsurface cement mines:
- Illinois Clay Products Mine, 1913-1924
- Reynolds Clay Mine
- Marquette Cement Mine
As well as several coal mines:
- Jones Mine, 1865-1930
- Oglesby Mine, 1865-1919
- Deer Park Mine, 1900-1920
- Black Hollow Mine, circa
As of the census of 2010, there were 3,791 people. The 2000 census showed 1,583 households, and 1,016 families residing in the city. The population density was 911.6 people per square mile (352.0/km²). There were 1,701 housing units at an average density of 425.2 per square mile (164.2/km²). According to the 2010 census The racial makeup of the city was 95.70% White, 0.37% African American, 0.13% Native American, 0.74% Asian, and Hispanic or Latino of any race were 6.52% of the population.
Census 2000 stated that there were 1,583 households out of which 27.8% had children under the age of 18 living with them, 51.6% were married couples living together, 9.0% had a female householder with no husband present, and 35.8% were non-families. 31.5% of all households were made up of individuals and 18.3% had someone living alone who was 65 years of age or older. The average household size was 2.29 and the average family size was 2.88.
In the city the population was spread out with 22.8% under the age of 18, 7.2% from 18 to 24, 28.2% from 25 to 44, 20.7% from 45 to 64, and 21.2% who were 65 years of age or older. The median age was 40 years. For every 100 females there were 91.3 males. For every 100 females age 18 and over, there were 91.2 males.
The median income for a household in the city was $35,000, and the median income for a family was $44,778. Males had a median income of $36,875 versus $20,331 for females. The per capita income for the city was $18,674. About 9.5% of families and 10.1% of the population were below the poverty line, including 14.0% of those under age 18 and 6.9% of those age 65 or over.
Notable people 
- Jim Bottomley (b.1900), first baseman for the St. Louis Cardinals, Cincinnati Reds and St. Louis Browns
- Frank Lamanske (b.1906), pitcher for the Brooklyn Dodgers
- Bo Molenda (b.1905), fullback (and later coach) for the Green Bay Packers and New York Giants; born in Oglesby
- "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.