List of Maine counties:

1. Androscoggin County: formed in 1854 from parts of Cumberland County, Kennebec County, Lincoln County, and Oxford County. County seat: Auburn.
2. Aroostook County: formed in 1839 from parts of Penobscot County, and Washington County. County seat: Houlton.
3. Cumberland County: formed in 1761 as Cumberland County, Massachusetts from part of York County. County seat: Portland.
4. Franklin County: formed in 1838 from parts of Kennebec County, Oxford County, and Somerset County. County seat: Farmington.
5. Hancock County: formed as Hancock County, Massachusetts in 1790 from part of Lincoln County. County seat: Ellsworth.
6. Kennebec County: formed as Kennebec County, Massachusetts in 1799 from part of Lincoln County. County seat: Augusta.
7. Knox County: formed in 1860 from parts of Lincoln County and Waldo County. County seat: Rockland.
8. Lincoln County: formed in 1760 from part of York County. County seat: Wiscasset.
9. Oxford County: formed in 1805 as Oxford County, Massachusetts from parts of Cumberland County and York County. County seat: Paris.
10. Penobscot County: formed in 1816 as Penobscot County, Massachusetts from part of Hancock County. County seat: Bangor.
11. Piscataquis County: formed in 1838 from parts of Penobscot County, and Somerset County. County seat: Dover-Foxcroft.
12. Sagadahoc County: formed in 1860 from part of Lincoln County. County seat: Bath.
13. Somerset County: formed in 1809 as Somerset County, Massachusetts from parts of Kennebec County. County seat: Skowhegan.
14. Waldo County: formed in 1827 as from parts of Hancock County, Kennebec County, and Lincoln County. County seat: Belfast.
15. Washington County: formed in 1790 as Washington County, Massachusetts from part of Lincoln County. County seat: Machias.
16. York County: formed in 1652 as Yorkshire County, Massachusetts from the southern part of the District of Maine. Renamed York County by Massachusetts in 1668. County seat: Alfred.