The Blue Mountains (Montagnes Bleues) is a 240 km long group of high hills along the Canada and United States border in the Eastern Townships. A northern extension of the White and Blue mountains of New England, these high hills have been locally called Monts Frontalières since at least the 1950s and were officially designated as Montagnes Bleues in 1985. They form a mountainous barrier along the border and their blue shade justifies the name.
The highest peaks are Mont Gosford (1186 m) and Mont Mégantic (1105 m). Mont Gosford is the highest mountain in southern Québec. Mont Mégantic is the site of an important astronomic observatory (1977) and a conservation park. This region is heavily forested and has a small population established in a few communities since the beginning of the 20th century.