Kosciusko is located on the Natchez Trace Parkway, northeast of Jackson. It is named for the Polish general Tadeusz Kościuszko, who assisted United States military efforts during the American Revolution. However the Anglicized name of the township omits the "z". Kosciusko was originally named Red Bud Springs for one of three natural springs that were present in the city. It is locally pronounced Kah-zee-ESS-ko.
According to the United States Census Bureau, the city has a total area of 7.6 square miles (19.6 km²), of which, 7.5 square miles (19.5 km²) of it is land and 0.13% is water. Kosciusko is one of the top 100 small cities to live in, in the United states
There were 2,885 households out of which 31.7% had children under the age of 18 living with them, 40.2% were married couples living together, 21.9% had a female householder with no husband present, and 33.9% were non-families. 31.2% of all households were made up of individuals and 17.5% had someone living alone who was 65 years of age or older. The average household size was 2.43 and the average family size was 3.04.
In the city the population was spread out with 26.2% under the age of 18, 9.5% from 18 to 24, 23.9% from 25 to 44, 19.8% from 45 to 64, and 20.6% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 82.7 males. For every 100 females age 18 and over, there were 77.1 males.
The median income for a household in the city was $21,737, and the median income for a family was $29,000. Males had a median income of $27,423 versus $16,487 for females. The per capita income for the city was $13,478. About 20.9% of families and 24.2% of the population were below the poverty line, including 31.9% of those under age 18 and 20.1% of those age 65 or over.