The City of Keithsburg was founded in 1837 by Robert Keith, a Scotchman, who emigrated to America in 1834. Keithsburg is also known as Middle Yellowbanks, being situated in the Yellowbanks Territory, a name given by the Sac and Fox Indians for the sandy yellow clay soil in the riverbanks. The Yellowbanks Territory, consisting of Keithsburg, New Boston and Oquawka became part of the Military Tract which entitled veterans of the War of 1812 to parcels of land as military bount.

Keithsburg is located at [show location on an interactive map] 41°6′0″N, 90°56′14″W (41.100020, -90.937293).
According to the United States Census Bureau, the city has a total area of 3.2 square miles (8.2 km²), of which, 2.6 square miles (6.7 km²) of it is land and 0.6 square miles (1.6 km²) of it (18.87%) is water.

Demographics
As of the census  of 2000, there were 714 people, 278 households, and 199 families residing in the city. The population density was 276.9 people per square mile (106.9/km²). There were 306 housing units at an average density of 118.7/sq mi (45.8/km²). The racial makeup of the city was 98.32% White, 0.28% Native American, and 1.40% from two or more races. Hispanic or Latino of any race were 0.42% of the population.
There were 278 households out of which 30.2% had children under the age of 18 living with them, 57.2% were married couples living together, 10.1% had a female householder with no husband present, and 28.1% were non-families. 24.5% of all households were made up of individuals and 16.9% had someone living alone who was 65 years of age or older. The average household size was 2.57 and the average family size was 2.96.
In the city the population was spread out with 26.9% under the age of 18, 7.7% from 18 to 24, 26.6% from 25 to 44, 22.1% from 45 to 64, and 16.7% who were 65 years of age or older. The median age was 36 years. For every 100 females there were 91.4 males. For every 100 females age 18 and over, there were 88.4 males.
The median income for a household in the city was $32,500, and the median income for a family was $40,781. Males had a median income of $27,000 versus $16,719 for females. The per capita income for the city was $14,008. About 10.3% of families and 14.0% of the population were below the poverty line, including 16.1% of those under age 18 and 4.8% of those age 65 or over.