Because of its proximity to Hazen, a town of similar size about 10 km (5 mi) away, Beulah is rarely mentioned by itself but rather as Beulah-Hazen. Beulah is home to the Dakota Gasification Company.
At the 2000 census, there were 3,152 people, 1,213 households, and 851 families residing in the city. The population density was 505.0/km² (1,307.8/mi²). There were 1,475 housing units at an average density of 236.3/km² (612.0/mi²). The racial makeup of the city was 95.78% White, 0.03% African American, 1.68% Native American, 0.29% Asian, 0.63% Pacific Islander, 0.16% from other races, and 1.43% from two or more races. Hispanic or Latino of any race were 0.48% of the population.
The top 6 ancestry groups in the city are German (74.3%), Norwegian (12.3%), Irish (9.3%), Russian (7.7%), English (3.4%), Czech (2.3%).
There were 1,213 households of which 39.9% had children under the age of 18 living with them, 61.0% were married couples living together, 6.8% had a female householder with no husband present, and 29.8% were non-families. 27.8% of all households were made up of individuals and 12.9% had someone living alone who was 65 years of age or older. The average household size was 2.53 and the average family size was 3.09.
Age distribution was 30.6% under the age of 18, 4.1% from 18 to 24, 27.9% from 25 to 44, 22.5% from 45 to 64, and 14.9% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 97.7 males. For every 100 females age 18 and over, there were 94.1 males.
The median household income was $45,256 and the median family income was $54,700. Males had a median income of $50,870 versus $20,792 for females. The per capita income for the city was $18,614. About 5.3% of families and 7.8% of the population were below the poverty line, including 4.6% of those under age 18 and 30.0% of those age 65 or over.