Troy is a city in Madison County, Illinois, United States. The population was 10,960 at the 2020 census, up from 9,888 in 2010. 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. History Troy was platted in 1819. It was incorporated as a town on February 18, 1857, and as a city in 1892. Geography Troy is located in south-central Madison County at (38.729236, -89.891733). It is bordered to the west by Maryville and to the northwest by Glen Carbon. Interstates 55 and 70 pass through the west side of Troy, with access from exits 17 and 18. The highways together lead southwest to St. Louis, while diverging just north of Troy: I-55 leads north to Springfield, the state capital, while I-70 leads east to Vandalia. U.S. Route 40 passes through the south side of Troy, joining I-55 and I-70 at the western edge of the city and leading east to Highland. Illinois Route 162 passes through the center of Troy as Center Street, Market Street, and Edwardsville Road, leading east to US 40 and west to the north part of Maryville. According to the U.S. Census Bureau, Troy has a total area of , of which are land and , or 0.92%, are water. Most of the city drains eastward into tributaries of Silver Creek, a south-flowing tributary of the Kaskaskia River. The westernmost part of the city drains to Canteen Creek, which flows southwest to the Mississippi River valley at East St. Louis. Demographics At the 2000 census there were 8,524 people in 3,100 households, including 2,356 families, in the city. The population density was . There were 3,201 housing units at an average density of . 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 3,100 households 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 households were one person and 6.8% were one person aged