1850 Counties of Maryland
| County | Description | Area in sq miles | Courts held at | Pop in 1850 |
| Alleghany | western part, Potomac river on north side, crossed by Alleghany Mts | 800 | Cumberland | 22,769 |
| Anne Arundel | west side of Patapsco river & Chesapeake Bay, Patuxent river on west. | 720 | Annapolis | 32,393 |
| Baltimore | in northernly part, north side Patapsco river, west side of ChesapeakeBay | 750 | Baltimore | 203,928 |
| Calvert | southern part, between Patuxent river and Chesapeake bay | 264 | Prince Frederick | 9,646 |
| Caroline | eastern boundary, on east side of Choptauk river | 240 | Denton | 9,962 |
| Carroll | north boundary, northwest side of Patapscp river | 500 | Westminster | 20,616 |
| Cecil | northeast corner, with Susquehanna river & Chesapeake bay on the west & southwest | 264 | Elkton | 18.939 |
| Charles | southwest part, on NE side of Potomac river | 450 | Port Tobacco | 16,162 |
| Dorchester | southeastern part, Chesapeake bay on the west | 640 | Cambridge | 18,877 |
| Frederick | northern boundary, Potomac river on the southwest | 750 | Fredericktown | 40,987 |
| Harford | northern boundary, Susquehanna river on northeast, Chesapeake bay on southeast | 480 | Belair | 19,356 |
| Kent | east boundary, Chesapeake bay on northwest | 240 | Chester | 11,386 |