Reinbeck resides in northeastern Iowa outside of the Waterloo-Cedar Falls area known as the Cedar Valley. Reinbeck is primarily an agricultural community that strives on the services of nearby larger cities like Cedar Falls.
As of the census of 2000, there were 1,751 people, 730 households, and 492 families residing in the city. The population density was 962.5 people per square mile (371.5/km²). There were 769 housing units at an average density of 422.7/sq mi (163.1/km²). The racial makeup of the city was 99.60% White, 0.11% African American, 0.17% Asian, 0.06% from other races, and 0.06% from two or more races. Hispanic or Latino of any race were 0.40% of the population.
There were 730 households out of which 28.2% had children under the age of 18 living with them, 58.8% were married couples living together, 6.7% had a female householder with no husband present, and 32.6% were non-families. 29.9% of all households were made up of individuals and 17.8% had someone living alone who was 65 years of age or older. The average household size was 2.33 and the average family size was 2.87.
In the city the population was spread out with 23.5% under the age of 18, 6.3% from 18 to 24, 25.3% from 25 to 44, 21.5% from 45 to 64, and 23.4% who were 65 years of age or older. The median age was 42 years. For every 100 females there were 90.5 males. For every 100 females age 18 and over, there were 84.6 males.
The median income for a household in the city was $36,667, and the median income for a family was $45,938. Males had a median income of $32,829 versus $21,618 for females. The per capita income for the city was $19,814. About 3.3% of families and 4.0% of the population were below the poverty line, including 2.3% of those under age 18 and 6.1% of those age 65 or over.