Dunbartonshire or the County of Dumbarton is a historic county, lieutenancy area and registration county in the west central Lowlands of Scotland lying to the north of the River Clyde. Dunbartonshire borders Perthshire to the north, Stirlingshire to the east, Lanarkshire and Renfrewshire to the south, and Argyllshire to the west.

Perthshire, officially the County of Perth, is a historic county and registration county in central Scotland. Geographically it extends from Strathmore in the east, to the Pass of Drumochter in the north, Rannoch Moor and Ben Lui in the west, and Aberfoyle in the south; it borders the counties of Inverness-shire and Aberdeenshire to the north, Angus to the east, Fife, Kinross-shire, Clackmannanshire, Stirlingshire and Dunbartonshire to the south and Argyllshire to the west. It was a local government county from 1890 to 1930.