St. Mary's County, Maryland Demographics 2026
St. Mary's County, Maryland has a population of 115,126, the 12th most populous county in Maryland. The median household income is $119,446 and the median home value is $407,600. The poverty rate is 8.0%.
Data vintage: U.S. Census Bureau ACS 2020–2024 5-Year Estimates · refreshed July 2026 · Methodology & source notes
St. Mary's County Quick Facts
How St. Mary's County Changed
Change from the 2019–2023 ACS period to 2020–2024. These are rolling five-year estimates, not year-over-year measurements.
| Metric | 2019–2023 | 2020–2024 | Change |
|---|---|---|---|
| Population | 114,372 | 115,126 | +0.7% |
| Median household income | $114,580 | $119,446 | +4.2% |
| Median home value | $390,900 | $407,600 | +4.3% |
Median Household Income
Median Home Value
Economy & Housing
Household Income Distribution
Detailed income brackets
Employment
Housing Overview
People & Demographics
Age Distribution
Race & Ethnicity
Diversity Index
Moderate diversity with one or two groups making up the majority.
State average: 68 | National average: 61
Education
Educational Attainment (Adults 25+)
Cities & Places in St. Mary's County
| City | Population | Median Income | Poverty | Home Value |
|---|---|---|---|---|
| Lexington Park | 13,252 | $94,799 | 13.8% | $309,700 |
| California | 13,136 | $119,855 | 6.9% | $346,800 |
| Wildewood | 7,552 | $126,890 | 4.7% | $383,400 |
| Leonardtown | 4,808 | $153,819 | 1.6% | $575,300 |
| Golden Beach | 3,830 | $133,194 | 2.7% | $382,700 |
| Mechanicsville | 1,395 | $120,966 | 2.9% | $416,100 |
| Piney Point | 1,274 | $129,018 | 7.3% | $336,600 |
| Charlotte Hall | 1,172 | $84,271 | 20.3% | $367,800 |
| Callaway | 930 | $160,341 | 5.8% | $364,700 |
| Tall Timbers | 391 | $195,982 | 4.6% | $732,600 |
| St. George Island | 277 | $250,000+ | 0.0% | $788,000 |
Explore Maryland Rankings
Population Overview
St. Mary's County is located in Maryland with a total population of 115,126. It is the 12th most populous county out of 24 in Maryland. The county encompasses 11 Census-designated places.
Age Demographics
The median age in St. Mary's County is 37.2 years. This is 6% lower than the state median of 39.4 years.
Economy, Income & Housing
The median household income in St. Mary's County is $119,446. This is 15% higher than the state median of $103,678. It is also 48% higher than the national median of $80,734. The poverty rate stands at 8.0%. This is 16% lower than the state poverty rate of 9.4%. The unemployment rate is 3.6%. This is 27% lower than the state rate of 4.9%. The median home value is $407,600. Housing costs are 3% lower than the state median of $419,900. The home-value-to-income ratio is 3.4x. 73.2% of occupied housing units are owner-occupied. This homeownership rate is 8% higher than the state average of 67.6%.
Race & Ethnicity
The largest racial or ethnic group in St. Mary's County is White (non-Hispanic), making up 70.3% of the population. Black or African American residents account for 14.5%. The White (non-Hispanic) population is significantly higher than the state average (70.3% vs 46.6%). The Hispanic or Latino population (6.1%) is well below the state average of 12.5%. The Asian population (2.6%) is well below the state average of 6.5%.
Education
36.5% of residents aged 25 and older hold a bachelor's degree or higher. This is 16% lower than the state rate of 43.5%. Nationally, 35.7% of adults hold at least a bachelor's degree. The high school graduation rate (or equivalent) is 92.7%. Notably, 16.2% of adults hold a graduate or professional degree, indicating a highly educated workforce.
Data Sources & Methodology
All figures for St. Mary's County come from the U.S. Census Bureau's American Community Survey (ACS) 2020–2024 5-Year Estimates, with comparisons drawn against Maryland and national averages from the same dataset. See our methodology page for how each metric is defined, or data.census.gov for official tables with margins of error.
Frequently Asked Questions
What is the population of St. Mary's County, Maryland?
St. Mary's County has a population of 115,126, making it the 12th most populous county in Maryland.
What is the median income in St. Mary's County?
The median household income in St. Mary's County is $119,446 with a poverty rate of 8.0%.
How many cities are in St. Mary's County, Maryland?
St. Mary's County contains 11 Census-designated places.