[1] The district was created in 1975 under the Local Government (Scotland) Act 1973, which established a two-tier structure of local government across mainland Scotland comprising upper-tier regions and lower-tier districts.

The district covered the whole area of five former districts and part of a sixth from the historic county of Dunbartonshire, which were all abolished at the same time:[2] The main urban areas were Dumbarton and the Vale of Leven settlements just to its north, and the town of Helensburgh and neighbouring coastal villages on the Firth of Clyde.

Further west, the terrain was increasingly mountainous and sparsely populated (much lying beyond the Highland Boundary Fault).

(Scotland) Act 1994 which replaced regions and districts with unitary council areas.

In the lead-up to the reforms a referendum was held in which the more rural west of the district, including Helensburgh, voted to join Argyll and Bute rather than stay with Dumbarton.