The largest county in Maryland
There are two right answers. By land area it is Frederick County; by population it is Montgomery County. Which one you want depends on what you meant by largest.
Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025. Retrieved 30 August 2026.
By land area
| Rank | Name | Land area | Population |
|---|---|---|---|
| 1 | Frederick County | 660.6 sq mi | 302,883 |
| 2 | Garrett County | 649.1 sq mi | 28,370 |
| 3 | Baltimore County | 598.4 sq mi | 847,650 |
| 4 | Dorchester County | 540.8 sq mi | 33,628 |
| 5 | Montgomery County | 493.1 sq mi | 1,074,582 |
| 6 | Prince George's County | 482.6 sq mi | 970,374 |
| 7 | Worcester County | 468.3 sq mi | 54,459 |
| 8 | Charles County | 457.8 sq mi | 176,593 |
| 9 | Washington County | 457.8 sq mi | 157,731 |
| 10 | Carroll County | 447.6 sq mi | 176,677 |
By population
| Rank | Name | Population | Density |
|---|---|---|---|
| 1 | Montgomery County | 1,074,582 | 2,179 per sq mi |
| 2 | Prince George's County | 970,374 | 2,011 per sq mi |
| 3 | Baltimore County | 847,650 | 1,417 per sq mi |
| 4 | Anne Arundel County | 603,380 | 1,455 per sq mi |
| 5 | Baltimore city | 569,997 | 7,042 per sq mi |
| 6 | Howard County | 339,183 | 1,352 per sq mi |
| 7 | Frederick County | 302,883 | 458 per sq mi |
| 8 | Harford County | 266,446 | 610 per sq mi |
| 9 | Carroll County | 176,677 | 395 per sq mi |
| 10 | Charles County | 176,593 | 386 per sq mi |
And the smallest
More on Maryland
Rebuilt from source data 30 August 2026. How these figures are produced.