The town of Dearborn was first settled in 1782, and formed from the east side of the West Pond Plantation in 1812. Dearborn land was set off to Waterville (later to become part of Oakland) in 1815, 1822, and 1826; set off to Belgrade 1834 and 1839; and set off to Smithfield 1840. The remaining northeast corner of Dearborn surrendered its town status in 1841 and became a plantation, which in 1843 was annexed by Waterville, Maine. Then, in 1873 Waterville set off that land to become part of what is now Oakland.    
County boundary changes
Dearborn was first incorporated in 1812 in Kennebec County. In 1840 a former part of Dearborn was set off to Smithfield, and northern Kennebec County including Smithfield was set off to become the southern part of Somerset County, Maine.
- Mabel R. Whiting, and Georgiana Hewins Lilly, Records of Dearborn Maine (Winthrop, Me.: Daughters of the American Revolution, Patience Stanley Chapter, D.A.R., 1937). At the Maine State Library.
- Dearborn in Maine: an Encyclopedia (accessed 31 May 2013).
- Michael J. Leclerc, Genealogist's Handbook for New England Research, 5th ed. (Boston, Mass.: New England Historic Genealogical Society, 2012), 152. At various libraries (WorldCat); FHL Book 974 D27g 2012.
- Maine Historical Records Survey Project, Division of Professional and Service Projects, Work Projects Administration, Counties, Cities, Towns, and Plantations of Maine: a Handbook of Incorporations, Dissolutions, and Boundary Changes (Portland, Maine: The Survey, 1940), 73 (digital p. 82). A digital version is available via a link in the FamilySearch Catalog.
- Legal History of Dearborn, Maine in Maine Genealogy (accessed 2 October 2013).
- Waterville, Kennebec County, Maine in Maine Genealogy (accessed 2 October 2013).