 Welsh slate was in high demand as a construction material in the English industrial cities, and was transported to the new port by horse-drawn tramways.The Ffestiniog Railway, opened in 1836 as a gravity railway, with horses hauling the empty slate waggons back up to the quarries, was converted to steam operation in 1863, and trains ran straight onto the wharves.By 1873 116,000 tons (117,800 t) of slate were being shipped out of Porthmadog, and other trade was being developed.