| County | Rank | Change (2020) ↓ | 2025 Pop. | 2020 Pop. |
|---|---|---|---|---|
| Frederick County | 1 | 11.84% | 305,093 | 272,786 |
| Queen Anne's County | 2 | 8.1% | 54,084 | 50,033 |
| Charles County | 3 | 5.37% | 175,697 | 166,741 |
| Worcester County | 4 | 4.04% | 54,645 | 52,522 |
| Somerset County | 5 | 3.88% | 25,514 | 24,561 |
| Carroll County | 6 | 3.49% | 178,973 | 172,941 |
| Cecil County | 7 | 3.35% | 107,276 | 103,800 |
| Dorchester County | 8 | 2.89% | 33,471 | 32,530 |
| Calvert County | 9 | 2.32% | 95,066 | 92,915 |
| St. Mary's County | 10 | 2% | 116,277 | 113,999 |
| Caroline County | 11 | 1.97% | 33,925 | 33,270 |
| Harford County | 12 | 1.94% | 266,302 | 261,230 |
| Wicomico County | 13 | 1.8% | 105,428 | 103,565 |
| Washington County | 14 | 1.44% | 156,925 | 154,697 |
| Anne Arundel County | 15 | 1.35% | 597,052 | 589,106 |
| Howard County | 16 | 1.34% | 337,271 | 332,814 |
| Kent County | 17 | 1.04% | 19,319 | 19,120 |
| Talbot County | 18 | 0.94% | 37,841 | 37,488 |
| Montgomery County | 19 | 0.79% | 1,069,288 | 1,060,904 |
| Allegany County | 20 | -0.99% | 67,287 | 67,960 |
| Baltimore County | 21 | -1.32% | 842,137 | 853,387 |
| Prince George's County | 22 | -1.76% | 948,330 | 965,365 |
| Garrett County | 23 | -2.45% | 28,093 | 28,798 |
| Baltimore city | 24 | -4.4% | 557,503 | 583,157 |
Maryland's counties show varied growth patterns from 2020 to 2025. Frederick County leads with 11.84% annualized growth, followed by Queen Anne's County (8.1%) and Charles County (5.37%). The largest counties are Montgomery County (1,069,288), Prince George's County (948,330), and Baltimore County (842,137). Of the 24 counties in Maryland, 19 are growing while 5 have experienced population decline. Overall, counties averaged 2.04% annualized growth, with total population growing by 0.63% annually.