St. Mary's is a census-designated place (CDP) located in and governed by Clear Creek County, Colorado, United States. The CDP is a part of the DenverâÂÂAuroraâÂÂLakewood, CO Metropolitan Statistical Area. The population of the St. Mary's CDP was 333 at the United States Census 2020. The St. Mary's Glacier Metropolitan District and the St. Mary's Glacier Water & Sanitation District provide services. The Idaho Springs post office (Zip Code 80452) serves the area.
The St. Mary's CDP has an area of , including of water.
The United States Census Bureau initially defined the for the