St. Mary’s is a census-designated place (CDP) and Unincorporated community in Clear Creek County, Colorado, United States. The population was 251 at the 2000 census and 283 at the 2010 census.
St. Mary’s is located at 39°49′13″N 105°38′58″W / 39.82028°N 105.64944°W / 39.82028; -105.64944 (39.820181, -105.649349).
According to the United States Census Bureau, the CDP has a total area of 3.1 square miles (8.0 km), of which, 3.1 square miles (8.0 km) of it is land and 0.33% is water.
As of the census of 2000, there were 251 people, 110 households, and 61 families residing in the CDP. The population density was 82.1 people per square mile (31.7/km²). There were 240 housing units at an average density of 78.5 per square mile (30.3/km²). The racial makeup of the CDP was 94.82% White, 0.80% African American, 0.40% Asian, 3.98% from other races. Hispanic or Latino of any race were 10.36% of the population.
There were 110 households out of which 30.9% had children under the age of 18 living with them, 47.3% were married couples living together, 1.8% had a female householder with no husband present, and 44.5% were non-families. 31.8% of all households were made up of individuals and none 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 3.02.
In the CDP, the population was spread out with 26.7% under the age of 18, 7.2% from 18 to 24, 39.8% from 25 to 44, 25.9% from 45 to 64, and 0.4% who were 65 years of age or older. The median age was 32 years. For every 100 females, there were 118.3 males. For every 100 females age 18 and over, there were 135.9 males.
The median income for a household in the CDP was $46,719, and the median income for a family was $48,750. Males had a median income of $38,304 versus $31,071 for females. The per capita income for the CDP was $22,156. None of the population or families were below the poverty line.