As well as the traffic for Ayr, the G&SWR ran trains to Carlisle over the route as far as Dalry, then diverging to Kilmarnock.
This gave the G&SWR an independent route from its Glasgow passenger terminal, St Enoch station, and its principal goods depot there, at College.
This line gave a closer connection to the Linwood pits, to Johnstone Gas Works, and to ironworks and foundries that were established north of the town.
[4][5][6] At Elderslie, westbound trains had either continued on the old main line via Howwood, or diverged to the right for Cart Junction and Greenock.
When the original main line was built, the Glasgow, Paisley and Johnstone Canal was crossed here by a bridge.
The canal was long since defunct, but the bridge was on a suitable alignment, and the dive-under line was made so as to use it.
[7] The line had about twelve return passenger journeys a day, running from Glasgow St Enoch to Ardrossan, Ayr, Kilmarnock and Largs.
[8] A casualty of the Beeching Axe, the line closed to regular passenger traffic on 27 June 1966.
The majority of the trackbed is now part of National Cycle Route 7, which runs from Carlisle to Inverness via Glasgow.
The Dalry and North Johnstone line opened from Cart Junction to Brownhills Junction on 1 June 1905, and on that date the original North Johnstone branch was downgraded to goods branch line status.