St. Mary's County, MD Demographics
St. Mary's County, MD is the 12th most populous of 24 counties in Maryland, with 113,777 residents across 359 square miles. That is about 317 people per square mile.
At the 2020 census
| Population | 113,777 |
|---|---|
| Land area | 359 sq mi |
| Density | 317 / sq mi |
Data: 2020 Census · American Community Survey 2024
How St. Mary's County compares to the US
We're computing this county's comparison table — check back shortly. Population, land area, and density above are already exact.
Central Location: St. Mary's County, MD
Measured from the county's main population center using 2020 census blocks.
We're computing the drive-time and radius areas around St. Mary's County, MD — check back shortly. Meanwhile you can drop a pin anywhere in the radius tool.
Census tracts in St. Mary's County, MD
| Name | Population | Sq mi | Per sq mi |
|---|---|---|---|
| Census Tract 8755.01 | 7,514 | 17.2 | 437 |
| Census Tract 8757 | 7,442 | 26.5 | 281 |
| Census Tract 8756.02 | 7,113 | 10.9 | 651 |
| Census Tract 8754 | 6,761 | 28.4 | 238 |
| Census Tract 8762 | 6,494 | 42.0 | 155 |
| Census Tract 8760.04 | 6,350 | 3.0 | 2,100 |
| Census Tract 8750 | 6,323 | 21.1 | 300 |
| Census Tract 8752.02 | 5,919 | 27.4 | 216 |
| Census Tract 8752.01 | 5,614 | 27.1 | 207 |
| Census Tract 8758.03 | 5,609 | 17.2 | 327 |
| Census Tract 8760.01 | 5,506 | 2.5 | 2,224 |
| Census Tract 8751 | 5,371 | 20.9 | 257 |
| Census Tract 8759.04 | 5,216 | 5.9 | 888 |
| Census Tract 8755.02 | 5,125 | 16.7 | 306 |
| Census Tract 8759.06 | 5,081 | 5.6 | 911 |
| Census Tract 8761.01 | 4,781 | 24.6 | 195 |
| Census Tract 8760.03 | 3,434 | 9.3 | 368 |
| Census Tract 8753 | 3,263 | 24.3 | 134 |
| Census Tract 8761.02 | 3,135 | 11.5 | 273 |
| Census Tract 8759.05 | 2,738 | 3.3 | 831 |
| Census Tract 8759.03 | 2,619 | 1.0 | 2,628 |
| Census Tract 8756.01 | 2,369 | 12.1 | 195 |
Related places
Other counties nearby
Nearest counties
Metro areas containing St. Mary's County
About this page
This page shows demographics for a US county from the 2020 census and the American Community Survey: population, land area, density, urban share, and how the county compares to national averages for income, housing, age, and more.
Counties subdivide into census tracts, listed below with their populations. The drive-time and radius tables measure the population around the county's main population center.