Narrow-gauge railways were used extensively in the slate industry of Great Britain, especially in Wales. Many quarries had internal tramways, some using many dozens of miles of track. Others had private lines that stretched from the quarry to transhipment points on local railways, rivers, roads or coastal ports.

The slate industry is the industry related to the extraction and processing of slate. Slate is either quarried from a slate quarry or reached by tunneling in a slate mine. Common uses for slate include as a roofing material, a flooring material, gravestones and memorial tablets, and electrical insulation.