St. Mary is a home rule-class city[5] in Marion County, Kentucky, in the United States.

[citation needed] The community was the birthplace and hometown of George Elder, who – along with William Byrne – later returned from seminary in Maryland to found Saint Mary's College in 1821.

The city includes historical markers honoring the Sisters of Loretto and St. Mary's College.

[7] St. Mary is located on Kentucky Route 84 at 37°50′56.6″N 85°20′46.7″W / 37.849056°N 85.346306°W / 37.849056; -85.346306 (37.580711, -85.346291),[8] 5 miles (8 km) west of Lebanon.

[4] Since 1980, St. Mary has been home to the 826-bed Marion Adjustment Center, a CCA-owned minimum- and medium-security facility.