Who lives in Marine today, how it compares with the county and the state, and how the population has changed since the mill era.
The short version
The 2020 census counted 664 people in Marine on St. Croix, spread across about 4.2 square miles — a density of only around 170 people per square mile of land, low for a city inside the Twin Cities metro area.
Compared with Washington County and with Minnesota as a whole, Marine is older, more likely to own its homes and more highly educated, and its housing stock is much older — the median home here was built around 1962, compared with 1992 countywide. A large share of residents work from home, which fits a village that is a long commute from most job centers.
These estimates come from the Census Bureau’s American Community Survey, which samples a small share of households every year. In a city this small, the margins of error are large, so the exact figures move around from year to year. The big differences — age, home ownership and the age of the houses — are consistent across surveys.
Last reviewed October 1, 2026.
664residents in 2020U.S. Census
57.3median ageyears
94%of homes owner-occupied
1,962median year builtfor housing units
Marine compared with the county and state
Measure
Marine on St. Croix
Washington County
Minnesota
Median age
57.3 yrs
39.8 yrs
38.8 yrs
Median household income
$126,250
$115,345
$89,062
Median home value
$470,100
$422,000
$329,300
Homes owner-occupied
94%
81%
72%
Adults with a bachelor's degree or higher
70%
49%
39%
Workers who work from home
30%
24%
18%
Average commute (minutes)
32
24
23
Median year homes were built
1962
1992
1979
Average household size
2.31
2.58
2.43
American Community Survey 5-year estimates, 2020-2024. For a place this small the margins of error are wide — the population estimate is 740 ± 124 — so treat single numbers as approximate and focus on the large differences.
