Ellsworth is a city in and the county seat of Hancock County, Maine, United States. The 2010 Census determined it had a population of 7,741. Ellsworth was Maine's fastest growing city from 2000–2010, with a growth rate of nearly 20 percent, but 2010-2014 saw only a gain of 102 people per Portland Press Herald data. With historic buildings and other points of interest, including the nearby Acadia National Park, Ellsworth is popular with tourists.
According to the history of the Passamaquoddy Indians, the Ellsworth area was originally inhabited by members of the Passamaquoddy and Penobscot tribes: "Both groups speak closely related Algonquian languages, although anthropologists generally group the Passamaquoddies linguistically with the Maliseets and the Penobscots with the Abenakis." 
George J. Varney, in the 'Hancock County, Maine' section of his Gazetteer of the State of Maine, published in Boston in 1886, wrote:
- "The first European who made definite mention of the Penobscot Bay and river, which wash its western side, was Thevet, a French explorer, in 1556. Martin Pring and Captain Weymouth, the English explorers, sailed along its shores in 1603 and 1605, and DeMonts, the Frenchman, explored some portions of the coast in 1604 and 1605. There is a tradition that Rosier, the historian of Weymouth's expedition, explored Deer Island thoroughfare, making a halt at the bold promontory in Brooksville, known as Cape Rosier. They found the county occupied by a tribe of Indians, who with those on Passamaquoddy waters, were noted for their long journeys in canoes; whence the general name for these Indians, Etechmins. DeMonts claimed the country in the name of the King of France in the true Catholic style, setting up a cross and calling the country "Acadie." By this name it continued to be known until the capture of Quebec by General James Wolfe in 1759. When Weymouth came in 1605, he also claimed the country in the name of his King, James I of England. Thus the two leading powers of Europe became adverse claimants of the soil of Hancock County, and the wars these claims occasioned kept the county an almost unbroken wilderness during the provincial history of Maine."
It is likely that the French who founded a colony at Somes Sound on Mount Desert Island in 1613, under the patronage of Madame de Guercheville, explored the Ellsworth area and what is now the watershed of the Union River.