History of Scottish Gaelic
All surviving dialects are Highland and/or Hebridean dialects. Dialects of Lowland Gaelic have become defunct since the demise of Galwegian Gaelic, originally spoken in Galloway, which seems to have been the last Lowland dialect and which survived into the Modern Period. By the 18th century Lowland Gaelic had been largely replaced by Lowland Scots across much of Lowland Scotland. According to a reference in "The Carrick Covenanters " by James Crichton, the last place in the Lowlands where Scottish Gaelic was still spoken was the village of Barr in Carrick: only a few miles inland to the east of Girvan, but at one time very isolated. Crichton gives neither date nor details.
Canadian Gaelic
Scottish Gaels settled in Nova Scotia commencing in 1773 with the arrival of the Ship Hector and continuing up until the 1850s. Gaelic has been spoken for 241 years in Nova Scotia: on Cape Breton Island and on the northeastern Nova Scotia mainland. During the early 1900s, the Gaelic language was nearly wiped out in Canadian schools.