MADAWASKA, Maine — Driving along Route 1A in northern Maine, it would be easy to think you had taken a wrong turn and ended up in Quebec. As you enter what locals simply call “The Valley,” signs appear in French along with the red, white, and blue of the Acadian flag.

This insular community stretches about 80 miles, from Hamlin to Allagash, including a string of towns where French is the most commonly spoken language. Census figures show 79.3 percent of the town of Frenchville’s population speaks the language — in the small city of Madawaska, two-thirds speak French as their first language.

Economic and demographic changes in The Valley, however, have left many locals afraid that French — or even their community — could peter out.

Locals say their concerns are threefold: Many young people are leaving the region to look for work in bigger cities, the transition from a primarily agrarian society has resulted in families having fewer children, and many of the young people who remain choose to speak English rather than French.

“Anyone in their 30s or younger, they’re speaking English,” said George Dionne, 63, sipping coffee on an early spring morning with friends at the Grand Isle General Store.

In 2000, 26 percent of Madawaska’s households had children under 18 living at home — by 2010 that number has dropped to 20 percent.

Sprawling families were once the norm in The Valley. On a recent day in Madawaska four sisters were sitting on a porch sipping coffee and conversing in French. The Sirois said they have 14 additional siblings, and in the 1950’s families of that size were quite common. Now, locals said families usually have two or three children at most.

And today, they said, you hear French less and less among youth.

“The language will soon be extinct,” one of the sisters said. “And that is sad.”