County
| FIPS Code [3] | Seat [4] | Established [4] | Origin
| Etymology
| Population [4][5] | Area [4][5] | Map
|
| Androscoggin County | 001 | Auburn | 1854 | From parts of Cumberland County, Kennebec County, and Lincoln County | The Androscoggin Native American tribe. | &0000000000103793.000000103,793 | &0000000000000497.000000497 mi² (1,287 km²) |  |
| Aroostook County | 003 | Houlton | 1839 | From parts of Penobscot County, and Washington County | A Native American word meaning beautiful river. | &0000000000073938.00000073,938 | &0000000000006829.0000006,829 sq mi (&0000000000017687.00000017,687 km2) |  |
| Cumberland County | 005 | Portland | 1761 | As Cumberland County, Massachusetts from part of York County | Prince William Augustus, Duke of Cumberland, son of George II of Great Britain. | &0000000000265612.000000265,612 | &0000000000001217.0000001,217 sq mi (&0000000000003152.0000003,152 km2) |  |
| Franklin County | 007 | Farmington | 1838 | From parts of Kennebec County, Oxford County, and Somerset County | Benjamin Franklin, the Founding Father, scientist, printer, and diplomat. | &0000000000029467.00000029,467 | &0000000000001744.0000001,744 sq mi (&0000000000004517.0000004,517 km2) |  |
| Hancock County | 009 | Ellsworth | 1790 | As Hancock County, Massachusetts, from part of Lincoln County | John Hancock (1737–1793), the Founding Father and president of the convention that produced the United States Declaration of Independence. | &0000000000051791.00000051,791 | &0000000000002351.0000002,351 sq mi (&0000000000006089.0000006,089 km2) |  |
| Kennebec County | 011 | Augusta | 1799 | As Kennebec County, Massachusetts from part of Lincoln County | The Kennebec River in Maine. | &0000000000117114.000000117,114 | &0000000000000951.000000951 sq mi (&0000000000002463.0000002,463 km2) |  |
| Knox County | 013 | Rockland | 1860 | From parts of Lincoln County and Waldo County | Henry Knox (1750–1806), the first United States Secretary of War (1789 - 1794), who lived in Thomaston, Maine. | &0000000000039618.00000039,618 | &0000000000001142.0000001,142 sq mi (&0000000000002958.0000002,958 km2) |  |
| Lincoln County | 015 | Wiscasset | 1760 | As Lincoln County, Massachusetts from part of York County | The city of Lincoln, England. | &0000000000033616.00000033,616 | &0000000000000700.000000700 sq mi (&0000000000001813.0000001,813 km2) |  |
| Oxford County | 017 | Paris | 1805 | As Oxford County, Massachusetts from parts of Cumberland County and York County | Probably named for Oxford, Massachusetts. | &0000000000054755.00000054,755 | &0000000000002175.0000002,175 sq mi (&0000000000005633.0000005,633 km2) |  |
| Penobscot County | 019 | Bangor | 1816 | As Penobscot County, Massachusetts from part of Hancock County | The Penobscot Native American tribe. | &0000000000144919.000000144,919 | &0000000000003556.0000003,556 sq mi (&0000000000009210.0000009,210 km2) |  |
| Piscataquis County | 021 | Dover-Foxcroft | 1838 | From parts of Penobscot County and Somerset County | An Abenaki word meaning rapid waters. | &0000000000017235.00000017,235 | &0000000000004377.0000004,377 sq mi (&0000000000011336.00000011,336 km2) |  |
| Sagadahoc County | 023 | Bath | 1860 | From part of Lincoln County | A Native American word meaning mouth of big river. | &0000000000035214.00000035,214 | &0000000000000370.000000370 sq mi (&0000000000000958.000000958 km2) |  |
| Somerset County | 025 | Skowhegan | 1809 | As Somerset County, Massachusetts from parts of Kennebec County | The county of Somerset in England. | &0000000000050888.00000050,888 | &0000000000004095.0000004,095 sq mi (&0000000000010606.00000010,606 km2) |  |
| Waldo County | 027 | Belfast | 1827 | From parts of Hancock County, Kennebec County and Lincoln County | Samuel Waldo, a colonial soldier in the siege of Louisbourg in 1745. | &0000000000036280.00000036,280 | &0000000000000853.000000853 sq mi (&0000000000002209.0000002,209 km2) |  |
| Washington County | 029 | Machias | 1790 | As Washington County, Massachusetts from part of Lincoln County | George Washington, the first President of the United States. | &0000000000033941.00000033,941 | &0000000000003255.0000003,255 sq mi (&0000000000008430.0000008,430 km2) |  |
| York County | 031 | Alfred | 1652 | As Yorkshire County, Massachusetts from the southern part of the District of Maine. Renamed York County by Massachusetts in 1668 | King James II of England, earlier Duke of York. | &0000000000186742.000000186,742 | &0000000000001271.0000001,271 sq mi (&0000000000003292.0000003,292 km2) |  |
A song is taught to many elementary school children across the state, entitled the Maine County Song, to aid in memorizing the names of the state's 16 counties. It is sung to the tune of Yankee Doodle.