River Falls is located 25 miles southeast of downtown St. Paul, Minnesota and is part of the Minneapolis/St. Paul Metropolitan Statistical Area, along with the rest of Pierce and St. Croix Counties.
As of the census of 2000, there were 12,560 people, 4,269 households, and 2,335 families residing in the city. The population density was 2,524.0 people per square mile (973.8/km²). There were 4,346 housing units at an average density of 873.2/sq mi (336.9/km²). The racial makeup of the city was 96.57% White, 0.53% Black or African American, 0.36% Native American, 1.02% Asian, 0.09% Pacific Islander, 0.32% from other races, and 1.12% from two or more races. Hispanic or Latino of any race were 0.95% of the population.
There were 4,269 households out of which 29.1% had children under the age of 18 living with them, 42.7% were married couples living together, 9.1% had a female householder with no husband present, and 45.3% were non-families. 27.7% of all households were made up of individuals and 9.1% 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 2.98.
In the city the population was spread out with 17.9% under the age of 18, 35.1% from 18 to 24, 23.8% from 25 to 44, 14.6% from 45 to 64, and 8.6% who were 65 years of age or older. The median age was 24 years. For every 100 females there were 83.5 males. For every 100 females age 18 and over, there were 80.1 males.
The median income for a household in the city was $41,184, and the median income for a family was $60,253. Males had a median income of $36,275 versus $27,345 for females. The per capita income for the city was $17,667. About 4.4% of families and 14.9% of the population were below the poverty line, including 6.6% of those under age 18 and 11.1% of those age 65 or over.