Penobscot County, ME
History
Penobscot County is the third largest in population of the sixteen counties, located in east central Maine, bisected by the Penobscot River and, the newer avenue of transportation, Interstate 95.Formed on April 1, 1816 from the northern part of what was then Hancock County, it later gave up territory to form Piscataquis and Aroostook counties. As with many counties, towns and borders changed throughout the early 19th century.
Source: http://maineanencyclopedia.com/penobscot-county/