Marine on St. Croix is a city in Washington County, Minnesota, United States. The population was 689 at the 2010 census. It was founded in 1839 as Marine Mills. The city was the site of the first commercial sawmill on the St. Croix River. A substantial portion of the city is listed as a historic district on the National Register of Historic Places and by the state of Minnesota.
According to the United States Census Bureau, the city has a total area of 4.17 square miles (10.80 km); 3.88 square miles (10.05 km) is land and 0.29 square miles (0.75 km) is water. Minnesota State Highway 95 serves as a main route in the community. The city is located at 45.19804 N, 92.77316 W.
As of the census of 2010, there were 689 people, 302 households, and 196 families residing in the city. The population density was 177.6 inhabitants per square mile (68.6/km). There were 348 housing units at an average density of 89.7 per square mile (34.6/km). The racial makeup of the city was 98.7% White, 0.1% African American, 0.4% Asian, 0.1% from other races, and 0.6% from two or more races. Hispanic or Latino of any race were 0.6% of the population.
There were 302 households of which 27.5% had children under the age of 18 living with them, 56.0% were married couples living together, 6.3% had a female householder with no husband present, 2.6% had a male householder with no wife present, and 35.1% were non-families. 29.8% of all households were made up of individuals and 11.6% had someone living alone who was 65 years of age or older. The average household size was 2.28 and the average family size was 2.84.
The median age in the city was 50 years. 21.8% of residents were under the age of 18; 3.6% were between the ages of 18 and 24; 13.2% were from 25 to 44; 42% were from 45 to 64; and 19.4% were 65 years of age or older. The gender makeup of the city was 47.2% male and 52.8% female.
As of the census of 2000, there were 602 people, 254 households, and 178 families residing in the city. The population density was 152.8 people per square mile (59.0/km²). There were 290 housing units at an average density of 73.6 per square mile (28.4/km²). The racial makeup of the city was 98.34% White, 0.33% African American, 0.17% Asian, and 1.16% from two or more races. Hispanic or Latino of any race were 0.17% of the population.
There were 254 households out of which 29.5% had children under the age of 18 living with them, 61.8% were married couples living together, 5.9% had a female householder with no husband present, and 29.9% were non-families. 23.6% of all households were made up of individuals and 7.1% had someone living alone who was 65 years of age or older. The average household size was 2.37 and the average family size was 2.83.
In the city, the population was spread out with 22.4% under the age of 18, 3.3% from 18 to 24, 26.1% from 25 to 44, 35.4% from 45 to 64, and 12.8% who were 65 years of age or older. The median age was 44 years. For every 100 females, there were 96.1 males. For every 100 females age 18 and over, there were 93.8 males.
The median income for a household in the city was $66,250, and the median income for a family was $77,633. Males had a median income of $51,705 versus $37,232 for females. The per capita income for the city was $32,383. About 3.1% of families and 2.8% of the population were below the poverty line, including 2.0% of those under age 18 and 5.4% of those age 65 or over.