List of Maryland counties and independent city*:
  1. Allegany County: formed in 1789 from part of Washington County. County seat: Cumberland.
  2. Anne Arundel County: formed in 1650 from unorganized territory. County seat: Annapolis.
  3. Baltimore City: founded in 1729. Detached* in 1851 from Baltimore County.
  4. Baltimore County: formed in 1659 from unorganized territory. County seat: Towson.
  5. Calvert County: formed in 1654 as Patuxent County from unorganized territory. Renamed Calvert County. County seat: Prince Frederick.
  6. Caroline County: formed in 1789 from parts of Dorchester County and Queenn Anne's County. County seat: Denton.
  7. Carroll County: formed in 1837 from parts of Baltimore County and Frederick County. County seat: Westminster.
  8. Cecil County: formed in 1837 from parts of Baltimore County and Kent County. County seat: Elkton.
  9. Charles County: formed in 1658 from unorganized territory. County seat: La Plata.
  10. Dorchester County: formed in 1668 from unorganized territory. County seat: Cambridge.
  11. Frederick County: formed in 1748 from part of Prince George's County. County seat: Frederick.
  12. Garrett County: formed in 1872 from part of Allegany County. County seat: Oakland.
  13. Harford County: formed in 1773 from part of Baltimore County. County seat: Bel Air.
  14. Howard County: formed in 1851 from parts of Anne Arundel County and Baltimore County. County seat: Ellicott City.
  15. Kent County: formed in 1642 from unorganized territory. County seat: Chestertown.
  16. Montgomery County: formed in 1776 from part of Frederick County. County seat: Rockville.
  17. Prince George's County: formed in 1695 from parts of Calvert County and Charles County. County seat: Upper Marlboro.
  18. Queen Anne's County: formed in 1706 from part of Talbot County. County seat: Centerville.
  19. St. Mary's County: formed in 1637 from unorganized territory. County seat: Leonardtown.
  20. Somerset County: formed in 1666 from unorganized territory. County seat: Princess Anne.
  21. Talbot County: formed in 1662 from part of Kent County. County seat: Easton.
  22. Washington County: formed in 1776 from part of Frederick County. County seat: Hagerstown.
  23. Wicomico County: formed in 1867 from parts of Somerset County and Worcester County. County seat: Salisbury.
  24. Worcester County: formed in 1742 from part of Somerset County. County seat: Snow Hill.
*Though an independent city rather than a county, the City of Baltimore is considered the equal of a county for most purposes.

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