The road was built in 1801 to permit slates from Diffws-Casson Quarry to be transported by carts to quays on the Dwyryd estuary. The quarry continued to use this means of transport until at least 1860, when it was at last connected to the Ffestiniog Railway via the Votty-Bowydd incline, and from 1863 by its own incline. A water-powered slate mill, Pant-yr-ynn (NPRN 28620) was built adjacent to the road in 1846; later it became a school and in 1881 a woollen mill.

W J Crompton, RCAHMW, 8 December 2011.