Heading west along the south coast of Scotland from its junction with the A74(M) motorway at Gretna it continues past Eastriggs, Annan, Dumfries, Castle Douglas, Gatehouse of Fleet, Newton Stewart, Kirkcowan and Glenluce before ending at Stranraer.

The road is widely felt to be unfit for the current large volumes of freight using it, but successive Westminster and laterly Scottish Governments have repeatedly shelved previously planned substantive upgrades, and delayed much needed, meaningful, investment in the route for decades, believed to be a root cause of Wigtownshire now being one of the most deprived areas of the UK.

[4] In case of the construction of an Irish Sea Bridge from Great Britain to Northern Ireland (Wigtownshire to Antrim), further road widening and potentially an upgrade to motorway status[according to whom?]

[citation needed] The mostly single-carriageway road has been re-aligned, re-routed and bypasses most towns in recognition of the heavy freight traffic it carries between the A74(M)/M6 and the ferry ports for Northern Ireland at Cairnryan.

[5] The new section claimed the title after the previous road was declassified and closed at the western end, allowing only local access to residential property and agricultural land.

Bypasses at Glenluce, Shennanton, Newton Stewart, Blackcraig, Creetown, Carsluith, Skyreburn, Gatehouse of Fleet/Barharrow, Tywnholm, Valleyfield, Ringford, Bridge of Dee, Castle Douglas, Ramhill, Southpark, Dumfries, Collin, Raffles, Carrutherstown, Annan and Gretna along with substantial re-alignment elsewhere were built during the 80's and 90's to form much of the current standard of road seen today.