Several areas of Maine received a large number of French-speaking immigrants during the 19th and 20th centuries, as Canadians moved from the provinces of Québec, Nova Scotia, Prince Edward Island, and New Brunswick to the industrial towns of New England. In Maine these included Biddeford, Lewiston-Auburn, Saco, and Rumford-Mexico; in the case of the Rumford-Mexico area a large Acadian population migrated from Prince Edward Island. Today approximately one-third of the population of Maine (336,127 people) describe themselves as being of French, French-Canadian, or Acadian ancestry (U.S. Census 1991b).

Starting in the mid-19th century, Maine Acadians migrated from the Valley to other locales in Maine, Massachusetts, Connecticut, and elsewhere. In many cases they clustered in what might be termed satellite cultural communities that maintain contact through family ties and return migration. Workers and their families first moved from the Upper St. John Valley in response to a shortage of millworkers in New England resulting from the Civil War. During the 20th century, mechanization increased the yield of farmland but reduced the number of laborers required. Facing a decline in employment opportunities in their home territory, many residents of the Valley headed south in search of jobs created by industrial growth. Bristol, Connecticut, for example, was one destination for Valley workers. A sizable group of Cyrs and Michauds with Valley roots now live in Missoula, Montana.

On July 5, 1991, Edgar Lavertu of Bristol, who returned to the Valley for the Lavertu family reunion, shared some of his experiences as an immigrant from the Valley. He explained that people who migrated to Bristol formed neighborhood "colonies," often consisting of extended families. The initial groups were located in urban settings, and he felt the migrant families maintained their distinct Valley culture to a surprising degree. However, as individual families gained the means to move to the suburbs, groups became more dispersed and traditions were harder to maintain.

Migration to and from the Valley (along with other factors) resulted in a 1990 population on the Maine side totaling approximately 27,000 (U.S. Census 1991a). The three international ports of entry--Fort Kent (pop. 4,268), Madawaska (pop. 4,803), and Van Buren (pop. 3,045)--are the largest U.S. towns in the Valley. Frenchville (pop. 1,338) and St. Agatha (pop.919) form a hub for the Valley's farming. The other villages in the region are considerably smaller. Some, especially toward the east, such as Grand Isle, Lille, and Keegan, were larger during the heyday of the St. John River log drives. The largest settlements in the Upper St. John Valley border the U.S. study area at Edmundston (pop. 12,044) and Grand Falls/Grand-Sault (pop. 6,203), New Brunswick.