Mandan is located just across the Missouri River from Bismarck. Mandan is home to the North Dakota Association of Rural Electric Cooperatives
As of the census of 2000, there were 16,718 people, 6,647 households, and 4,553 families residing in the city. The population density was 634.1/km² (1,642.8/mi²). There were 6,958 housing units at an average density of 263.9/km² (683.7/mi²). The racial makeup of the city was 94.98% White, 0.20% African American, 3.02% Native American, 0.33% Asian, 0.01% Pacific Islander, 0.15% from other races, and 1.30% from two or more races. Hispanic or Latino of any race were 0.78% of the population.
There were 6,647 households out of which 35.7% had children under the age of 18 living with them, 54.1% were married couples living together, 10.6% had a female householder with no husband present, and 31.5% were non-families. 26.4% of all households were made up of individuals and 10.1% had someone living alone who was 65 years of age or older. The average household size was 2.48 and the average family size was 3.01.
In the city the population was spread out with 27.0% under the age of 18, 9.0% from 18 to 24, 29.7% from 25 to 44, 21.6% from 45 to 64, and 12.7% who were 65 years of age or older. The median age was 36 years. For every 100 females there were 97.0 males. For every 100 females age 18 and over, there were 93.6 males.
The median income for a household in the city was $38,182, and the median income for a family was $46,210. Males had a median income of $31,653 versus $21,400 for females. The per capita income for the city was $17,509. About 7.0% of families and 10.0% of the population were below the poverty line, including 12.2% of those under age 18 and 13.6% of those age 65 or over.