Located in the north-western corner of New Brunswick, Madawaska County is bordered on the north by Restigouche County, on the east by Victoria County, on the west by Temiscouata County (Quebec), and on the south by Aroostook County (Maine). The genealogist researching records of the land that is now Madawaska county should understand the history of this area, and the evolution of its borders.

New Brunswick was first established in 1784 & comprised of eight counties; the western part of the province, including the land now known as Madawaska County, was originally York County. In 1831, the northern part of York County became Carleton County. The parishes (similar to US townships, & used as census sub-districts) of Perth, Madawaska & Andover were established in 1833. In 1844, Victoria County was created from the northern parts of Carleton County. The parishes of St. Leonard & St. Basil were established in 1850; Grand Falls, Gordon, Lorne, & Drummond were established in 1852, 1863, 1871, and 1872 (respectively). In 1873, the western half of Victoria County, including the parishes of Madawaska, St. Leonard, and St. Basile, became Madawaska County. The parishes of St. Francis, St. Hilaire, St. Jacques, & Ste-Anne were all established in Madawaska County in 1877.

Madawaska`s southern border has been no less dynamic. The 1783 Treaty of Versailles (ended American Revolution) established Maine`s eastern boundary at the St. Croix River. However, neither this agreement nor the subsequent 1815 Treaty of Ghent (ended War of 1812) established Maine`s northern & western borders, resulting in nearly a half-century of conflict (Aroostook War) between New Brunswick & Maine. The dispute was resolved bloodlessly with the negotiation of the Webster-Ashburton Treaty (adopted in 1842), finally establishing the border between Maine & New Brunswick. Because of this, & the continued shared culture, events from Aroostook County, Maine may show up in Madawaska County records & vice versa.