It was constructed between 12 August 1800 and October 1809, in the wake of the Irish Rebellion of 1798, to open up the mountains to Crown forces to assist them in tracking down United Irishmen insurgents who were hiding there.

From there it continues to a point east of Mullaghcleevaun Mountain (850 m) before descending to the village of Laragh, near Glendalough, via the scenic Glenmacnass waterfall.

For many years, the road was used as the Sally Gap special stage in the Circuit of Ireland car rally.

The road was upgraded from the Dublin border to Sally Gap in 1942, by the 3rd battalion of the Construction Corps, to allow for the harvesting of peat and for post-war tourists.

[6] The route from Sally Gap to Laragh was apparently overgrown during this period but upgraded in 1956, along with the addition of a car park at Glenmacnass Waterfall.