As of the census of 2000, there were 11,621 people, 4,760 households, and 3,070 families residing in the city. The population density was 2,154.8 people per square mile (832.4/km²). There were 4,983 housing units at an average density of 924.0/sq mi (356.9/km²). The racial makeup of the city was 96.09% White, 0.34% African American, 0.29% Native American, 0.60% Asian, 0.01% Pacific Islander, 1.87% from other races, and 0.79% from two or more races. Hispanic or Latino of any race were 4.37% of the population.
There were 4,760 households out of which 31.4% had children under the age of 18 living with them, 52.2% were married couples living together, 9.2% had a female householder with no husband present, and 35.5% were non-families. 29.4% of all households were made up of individuals and 12.7% had someone living alone who was 65 years of age or older. The average household size was 2.40 and the average family size was 2.96.
In the city the population was spread out with 24.2% under the age of 18, 8.6% from 18 to 24, 30.9% from 25 to 44, 21.8% from 45 to 64, and 14.5% who were 65 years of age or older. The median age was 36 years. For every 100 females there were 93.4 males. For every 100 females age 18 and over, there were 90.6 males.
The median income for a household in the city was $43,807, and the median income for a family was $51,689. Males had a median income of $36,442 versus $23,852 for females. The per capita income for the city was $21,008. 5.3% of the population and 3.9% of families were below the poverty line. Out of the total population, 4.7% of those under the age of 18 and 5.8% of those 65 and older were living below the poverty line.
Primary automobile transportation is provided via Highway 12, Highway 26, Highway 89 and Highway 106. Highway 26 provides easy access to Interstate 94 (to the north in Johnson Creek), leading to downtown Milwaukee in about an hour; and to Interstate 90 (to the south in Janesville) leading to downtown Chicago in about 2.5 hours. Highway 12 provides access to the Madison metro area in about 45 minutes. General aviation interests are served by the Fort Atkinson Municipal Airport.