The William W. Jarvis House, a historic site in the city.
|Area||5.35 sq mi (14 km2)|
|- land||5.29 sq mi (14 km2)|
|- water||0.06 sq mi (0 km2)|
|Density||1,865.7/sq mi (720/km2)|
|- summer (DST)||CDT (UTC-5)|
|Wikimedia Commons: Troy, Illinois|
Troy is part of the St. Louis Metropolitan Statistical Area. Its namesake in Lincoln County, Missouri is also part of this MSA, making it (along with the two O'Fallons in Illinois and Missouri) one of the few pairs of like-named municipalities to be part of the same MSA.
Troy is located at (38.729236, -89.891733).
According to the 2010 census, Troy has a total area of 5.349 square miles (13.85 km2), of which 5.29 square miles (13.70 km2) (or 98.9%) is land and 0.059 square miles (0.15 km2) (or 1.1%) is water.
As of the census of 2000, there were 8,524 people, 3,100 households, and 2,356 families residing in the city. The population density was 2,037.6 people per square mile (787.4/km²). There were 3,201 housing units at an average density of 765.2 per square mile (295.7/km²). The racial makeup of the city was 95.48% White, 1.48% African American, 0.32% Native American, 0.70% Asian, 0.38% from other races, and 1.64% from two or more races. Hispanic or Latino of any race were 1.49% of the population.
There were 3,100 households out of which 45.2% had children under the age of 18 living with them, 60.1% were married couples living together, 12.5% had a female householder with no husband present, and 24.0% were non-families. 19.5% of all households were made up of individuals and 6.8% had someone living alone who was 65 years of age or older. The average household size was 2.75 and the average family size was 3.16.
In the city the population was spread out with 30.2% under the age of 18, 8.6% from 18 to 24, 34.3% from 25 to 44, 19.2% from 45 to 64, and 7.7% who were 65 years of age or older. The median age was 33 years. For every 100 females there were 96.0 males. For every 100 females age 18 and over, there were 91.5 males.
The median income for a household in the city was $53,720, and the median income for a family was $59,643. Males had a median income of $41,705 versus $27,542 for females. The per capita income for the city was $21,174. About 2.1% of families and 3.4% of the population were below the poverty line, including 3.4% of those under age 18 and 4.5% of those age 65 or over.
- Paul Simon, US senator; lived in Troy and was the youngest editor of the town's newspaper (Troy Tribune)
- Jesse L. Simpson, Chief Justice of the Illinois Supreme Court; born in Troy
- Bob Turley, Cy Young Award-winning pitcher for the St. Louis Browns, Baltimore Orioles, New York Yankees, Los Angeles Angels, and Boston Red Sox; born in Troy
- "Profile of General Population and Housing Characteristics: 2010 Demographic Profile Data (DP-1): Troy city, Illinois". U.S. Census Bureau, American Factfinder. Retrieved January 20, 2012.
- Norton, William T. (1912). Centennial History of Madison County, Illinois, and Its People, 1812 to 1912. The Lewis Publishing Co. p. 560.
- "US Gazetteer files: 2010, 2000, and 1990". United States Census Bureau. 2011-02-12. Retrieved 2011-04-23.
- "G001 - Geographic Identifiers - 2010 Census Summary File 1". United States Census Bureau. Retrieved 2015-12-27.
- "Annual Estimates of the Resident Population for Incorporated Places: April 1, 2010 to July 1, 2015". Retrieved July 2, 2016.
- "Census of Population and Housing". Census.gov. Retrieved June 4, 2015.
- "American FactFinder". United States Census Bureau. Retrieved 2008-01-31.