| Official Name: | St. Mary's, Colorado |
| Settlement Type: | Census Designated Place |
| Pushpin Map: | USA |
| Pushpin Label Position: | right |
| Pushpin Map Caption: | Location of the St. Mary's CDP in the |
| Subdivision Type: | Country |
| Subdivision Type1: | State |
| Subdivision Type2: | County |
| Subdivision Name2: | Clear Creek County |
| Government Type: | unincorporated community |
| Unit Pref: | US |
| Area Footnotes: | [1] |
| Area Total Km2: | 3.744 |
| Area Land Km2: | 3.726 |
| Area Water Km2: | 0.018 |
| Population As Of: | 2020 |
| Population Footnotes: | [2] |
| Population Total: | 333 |
| Population Density Km2: | auto |
| Population Density Sq Mi: | auto |
| Timezone: | MST |
| Utc Offset: | -7 |
| Timezone Dst: | MDT |
| Utc Offset Dst: | -6 |
| Coordinates: | 39.8163°N -105.6479°W |
| Elevation M: | 3075 |
| Elevation Ft: | 10088 |
| Postal Code: | Idaho Springs 80452 |
| Area Codes: | 303 & 720 |
| Postal Code Type: | ZIP Code[3] |
| Blank Name: | GNIS feature[4] |
| Blank Info: | St. Mary's CDP |
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 Denver–Aurora–Lakewood, 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.[3]
The St. Mary's CDP has an area of 3.744km2, including 0.018km2 of water.[1]
The United States Census Bureau initially defined the for the