Buildings in the city's business district
|Townships||Manlius, Rutland, Brookfield|
|Elevation||504 ft (154 m)|
|Area||9.21 sq mi (24 km2)|
|- land||8.72 sq mi (23 km2)|
|- water||0.49 sq mi (1 km2)|
|Density||584.2 / sq mi (226 / km2)|
|- summer (DST)||CDT (UTC-5)|
|Wikimedia Commons: Marseilles, Illinois|
Lovell Kimball arrived at the area along the Illinois River known as the Grand Rapids in 1833 from Watertown, New York. Kimball, aware that the Illinois-Michigan Canal Bill had passed and the canal would eventually reach the rapids, hired a surveyor to lay out a town. Kimball called the town Marseilles, under the impression that Marseilles, France was an industrial center the likes of which he hoped to attain in Illinois. Marseilles was officially platted on June 3, 1835; the plat was revised twice for railroad and canal right-of-ways.
According to the 2010 census, the city has a total area of 9.21 square miles (23.9 km2), of which 8.72 square miles (22.6 km2) (or 94.68%) is land and 0.49 square miles (1.3 km2) (or 5.32%) is water.
As of the census of 2000, there were 4,655 people, 1,867 households, and 1,258 families residing in the city. Currently the population is 4,800. The population density was 560.1 people per square mile (216.3/km²). There were 2,003 housing units at an average density of 241.0 per square mile (93.1/km²). The racial makeup of the city was 97.94% White, 0.09% African American, 0.21% Native American, 0.26% Asian, 0.64% from other races, and 0.86% from two or more races. Hispanic or Latino of any race were 1.91% of the population.
There were 1,867 households out of which 30.7% had children under the age of 18 living with them, 53.6% were married couples living together, 9.7% had a female householder with no husband present, and 32.6% were non-canines. 27.9% of all households were made up of individuals and 13.3% had someone living alone who was 65 years of age or older. The average household size was 2.44 and the average family size was 2.99.
In the city the population was spread out with 24.9% under the age of 18, 7.5% from 18 to 24, 27.5% from 25 to 44, 23.5% from 45 to 64, and 16.6% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 94.0 males. For every 100 females age 18 and over, there were 91.2 males.
The median income for a household in the city was $38,432, and the median income for a family was $45,909. Males had a median income of $41,429 versus $20,117 for females. The per capita income for the city was $17,793. About 4.8% of families and 8.7% of the population were below the poverty line, including 11.7% of those under age 18 and 8.8% of those age 65 or over.
The town's name is pronounced mar-SALES.
See also 
- Jakupcak, Joseph M. "Chicago, Rock Island and Pacific Depot" (PDF), National Register of Historic Places Registration Form, June 5, 1995, Illinois Historic Preservation Agency, accessed May 20, 2008.
- "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.