|— City —|
|• Mayor||Mark Cross|
|• Total||7.34 sq mi (19.01 km2)|
|• Land||7.30 sq mi (18.91 km2)|
|• Water||0.04 sq mi (0.10 km2)|
|Elevation||545 ft (166 m)|
|• Estimate (2011)||10,641|
|• Density||1,443.8/sq mi (557.5/km2)|
|Time zone||CST (UTC-6)|
|• Summer (DST)||CDT (UTC-5)|
|GNIS feature ID||0727810|
Troy is part of the St. Louis Metropolitan Statistical Area. Its namesake in Madison County, Illinois 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 . According to the United States Census Bureau, the city has a total area of 7.34 square miles (19.01 km2), of which, 7.30 square miles (18.91 km2) is land and 0.04 square miles (0.10 km2) is water.(38.974922, -90.977132)
2010 census 
As of the census of 2010, there were 10,540 people, 3,843 households, and 2,727 families residing in the city. The population density was 1,443.8 inhabitants per square mile (557.5 /km2). There were 4,141 housing units at an average density of 567.3 per square mile (219.0 /km2). The racial makeup of the city was 92.5% White, 3.1% African American, 0.4% Native American, 0.7% Asian, 0.8% from other races, and 2.4% from two or more races. Hispanic or Latino of any race were 3.0% of the population.
There were 3,843 households out of which 43.6% had children under the age of 18 living with them, 50.5% were married couples living together, 14.8% had a female householder with no husband present, 5.6% had a male householder with no wife present, and 29.0% were non-families. 24.4% of all households were made up of individuals and 10.1% had someone living alone who was 65 years of age or older. The average household size was 2.67 and the average family size was 3.16.
The median age in the city was 32.2 years. 30.5% of residents were under the age of 18; 7.7% were between the ages of 18 and 24; 30.4% were from 25 to 44; 19.6% were from 45 to 64; and 11.8% were 65 years of age or older. The gender makeup of the city was 47.4% male and 52.6% female.
2000 census 
As of the census of 2000, there were 6,737 people, 2,521 households, and 1,747 families residing in the city. The population density was 1,134.5 people per square mile (437.9/km²). There were 2,661 housing units at an average density of 448.1 per square mile (173.0/km²). The racial makeup of the city was 93.87% White, 2.86% African American, 0.39% Native American, 0.13% Asian, 0.01% Pacific Islander, 0.80% from other races, and 1.93% from two or more races. Hispanic or Latino of any race were 1.71% of the population.
There were 2,521 households out of which 39.8% had children under the age of 18 living with them, 51.6% were married couples living together, 14.6% had a female householder with no husband present, and 30.7% were non-families. 26.6% of all households were made up of individuals and 12.5% had someone living alone who was 65 years of age or older. The average household size was 2.56 and the average family size was 3.10.
In the city the population was spread out with 29.8% under the age of 18, 9.2% from 18 to 24, 30.6% from 25 to 44, 16.4% from 45 to 64, and 14.0% who were 65 years of age or older. The median age was 32 years. For every 100 females there were 87.1 males. For every 100 females age 18 and over, there were 83.7 males.
The median income for a household in the city was $40,332, and the median income for a family was $46,818. Males had a median income of $34,750 versus $24,440 for females. The per capita income for the city was $17,666. About 7.6% of families and 11.0% of the population were below the poverty line, including 13.4% of those under age 18 and 14.6% of those age 65 or over.
Notable Sites 
Fort Cap au Gris, a War of 1812 fortification, was built near Troy in 1814. Lincoln County Medical Center was established in Troy in 1953 under the federal Hill-Burton Memorial Hospitals Act, as Lincoln County Memorial Hospital, and has generally been the largest employer in the city. Troy is home to Cuivre River State Park, one of the largest of Missouri's state parks.
Notable residents 
- William L. Hungate - U.S. Congressman and Federal Judge
- Frederick G. Bonfils - Publisher of the Denver Post
- Dennis Tankersley - Baseball Player San Diego Padres, St. Louis Cardinals (Minor League), Detroit Tigers (Minor League), Washington Nationals (Minor League)
- Nathaniel Simonds, State Treasurer of Missouri (1821–1829)
Omer H. Avery, former, Missouri State Senator and President Pro Tem of the Missouri Senate
Troy is home to Troy Buchanan High School, part of the Lincoln County R-III School District.
- "US Gazetteer files 2010". United States Census Bureau. Retrieved 2012-07-08.
- "American FactFinder". United States Census Bureau. Retrieved 2012-07-08.
- "Population Estimates". United States Census Bureau. Retrieved 2013-01-04.
- "American FactFinder". United States Census Bureau. Retrieved 2008-01-31.
- "US Board on Geographic Names". United States Geological Survey. 2007-10-25. Retrieved 2008-01-31.
- "Find a County". National Association of Counties. Retrieved 2011-06-07.
- "US Gazetteer files: 2010, 2000, and 1990". United States Census Bureau. 2011-02-12. Retrieved 2011-04-23.
- City of Troy, Missouri
- Historic maps of Troy in the Sanborn Maps of Missouri Collection at the University of Missouri
- Troy Weather