The City of Baltimore generally possesses the same powers and responsibilities as the counties within the state. It is an entity nearly surrounded by but separate from the County of Baltimore, which has its county seat in Towson.
County
| FIPS Code [5] | County seat [2][6] | Established [2][6] | Origin [2] | Etymolgy [2] | Population [6][7] | Area [6][7] | Map
|
| Allegany County | 001 | Cumberland | 1789 | Formed from part of Washington County. | From the Lenape Indian word oolikhanna, which means "beautiful stream" | &0000000000073639.00000073,639 | &0000000000000430.000000430 sq mi (&0000000000001114.0000001,114 km2) |  |
| Anne Arundel County | 003 | Annapolis | 1650 | Formed from part of St. Mary's County. | Anne Arundell was the maiden name of the wife of Cæcilius Calvert, 2nd Baron Baltimore. Between 1654 and 1658 it was known as Providence County by Puritan settlers | &0000000000510878.000000510,878 | &0000000000000588.000000588 sq mi (&0000000000001523.0000001,523 km2) |  |
| Baltimore County | 005 | Towson | 1659 | Formed from unorganized territory | Cæcilius Calvert, 2nd Baron Baltimore, first proprietor of the Maryland colony | &0000000000786113.000000786,113 | &0000000000000682.000000682 sq mi (&0000000000001766.0000001,766 km2) |  |
| Baltimore City | 510 | Baltimore City | 1851 | Founded in 1729. Detached in 1851 from Baltimore County | Cæcilius Calvert, 2nd Baron Baltimore, first proprietor of the Maryland colony | &0000000000641943.000000641,943 | &0000000000000092.00000092 sq mi (&0000000000000238.000000238 km2) |  |
| Calvert County | 009 | Prince Frederick | 1654 | Formed as Patuxent County from unorganized territory. Renamed Calvert County in 1658 | The Calvert family; prior to 1658 it was called Patuxent County, after the Patuxent Indians, a branch of the Algonquians | &0000000000086474.00000086,474 | &0000000000000345.000000345 sq mi (&0000000000000894.000000894 km2) |  |
| Caroline County | 011 | Denton | 1773 | From parts of Dorchester County and Queen Anne's County | Lady Caroline Eden, daughter of Charles Calvert, 5th Baron Baltimore | &0000000000029772.00000029,772 | &0000000000000326.000000326 sq mi (&0000000000000844.000000844 km2) |  |
| Carroll County | 013 | Westminster | 1837 | From parts of Baltimore County and Frederick County | Charles Carroll of Carrollton, a representative to the Continental Congress and signatory of the Declaration of Independence | &0000000000150897.000000150,897 | &0000000000000452.000000452 sq mi (&0000000000001171.0000001,171 km2) |  |
| Cecil County | 015 | Elkton | 1672 | From parts of Baltimore County and Kent County | Cecil is an Anglicized form of the first name of Cæcilius Calvert, 2nd Baron Baltimore | &0000000000097796.00000097,796 | &0000000000000418.000000418 sq mi (&0000000000001083.0000001,083 km2) |  |
| Charles County | 017 | La Plata | 1658 | From unorganized territory | Charles Calvert, 3rd Baron Baltimore, second proprietor of the Maryland colony | &0000000000120546.000000120,546 | &0000000000000643.000000643 sq mi (&0000000000001665.0000001,665 km2) |  |
| Dorchester County | 019 | Cambridge | 1668 | From unorganized territory | Dorchester in Dorset, England; the Earl of Dorset was a friend of the Calvert family | &0000000000030674.00000030,674 | &0000000000000983.000000983 sq mi (&0000000000002546.0000002,546 km2) |  |
| Frederick County | 021 | Frederick | 1748 | From part of Prince George's County | Frederick Calvert, 6th Baron Baltimore, final proprietor of the Maryland colony | &0000000000220701.000000220,701 | &0000000000000667.000000667 sq mi (&0000000000001728.0000001,728 km2) |  |
| Garrett County | 023 | Oakland | 1872 | From part of Allegany County | John Work Garrett, president of the Baltimore and Ohio Railroad | &0000000000029846.00000029,846 | &0000000000000656.000000656 sq mi (&0000000000001699.0000001,699 km2) |  |
| Harford County | 025 | Bel Air | 1773 | From part of Baltimore County | Henry Harford, illegitimate son of Frederick Calvert, 6th Baron Baltimore | &0000000000218590.000000218,590 | &0000000000000527.000000527 sq mi (&0000000000001365.0000001,365 km2) |  |
| Howard County | 027 | Ellicott City | 1851 | From parts of Anne Arundel County and Baltimore County | John Eager Howard, an American Revolutionary War officer and governor of Maryland | &0000000000269457.000000269,457 | &0000000000000254.000000254 sq mi (&0000000000000658.000000658 km2) |  |
| Kent County | 029 | Chestertown | 1642 | From unorganized territory | The English county of Kent | &0000000000019197.00000019,197 | &0000000000000414.000000414 sq mi (&0000000000001072.0000001,072 km2) |  |
| Montgomery County | 031 | Rockville | 1776 | From part of Frederick County | Richard Montgomery, an American Revolutionary War general | &0000000000927583.000000927,583 | &0000000000000507.000000507 sq mi (&0000000000001313.0000001,313 km2) |  |
| Prince George's County | 033 | Upper Marlboro | 1696 | From parts of Calvert County and Charles County | Prince George of Denmark, husband to Queen Anne I of Great Britain | &0000000000846123.000000846,123 | &0000000000000498.000000498 sq mi (&0000000000001290.0000001,290 km2) |  |
| Queen Anne's County | 035 | Centreville | 1706 | From parts of Talbot County | Anne I, Queen of Great Britain | &0000000000040563.00000040,563 | &0000000000000510.000000510 sq mi (&0000000000001321.0000001,321 km2) |  |
| Saint Mary's County | 037 | Leonardtown | 1637 | From unorganized territory. Was named Potomac County between 1654 and 1658. | The Virgin Mary, first county named in a colony intended to be a haven for Catholics | &0000000000086211.00000086,211 | &0000000000000611.000000611 sq mi (&0000000000001582.0000001,582 km2) |  |
| Somerset County | 039 | Princess Anne | 1666 | From unorganized territory. | Mary, Lady Somerset, sister-in-law of Cæcilius Calvert, 2nd Baron Baltimore | &0000000000024747.00000024,747 | &0000000000000611.000000611 sq mi (&0000000000001582.0000001,582 km2) |  |
| Talbot County | 041 | Easton | 1662 | From part of Kent County | Grace, Lady Talbot, sister of Cæcilius Calvert, 2nd Baron Baltimore | &0000000000033812.00000033,812 | &0000000000000477.000000477 sq mi (&0000000000001235.0000001,235 km2) |  |
| Washington County | 043 | Hagerstown | 1776 | From part of Frederick County | George Washington, first President of the United States | &0000000000143748.000000143,748 | &0000000000000468.000000468 sq mi (&0000000000001212.0000001,212 km2) |  |
| Wicomico County | 045 | Salisbury | 1867 | From parts of Somerset County and Worcester County | The Wicomico River; in Lenape, wicko mekee indicated "a place where houses are built," possibly in reference to a settlement | &0000000000084644.00000084,644 | &0000000000000400.000000400 sq mi (&0000000000001036.0000001,036 km2) |  |
| Worcester County | 047 | Snow Hill | 1742 | From part of Somerset County | Mary Arundell, the wife of Sir John Somerset, son of the 1st Marquess of Worcester, and sister of Anne Arundell, wife of Cæcilius Calvert, 2nd Baron Baltimore | &0000000000046543.00000046,543 | &0000000000000695.000000695 sq mi (&0000000000001800.0000001,800 km2) |  |