In 1913 the 232,000 men working in the 620 mines in South Wales produced 57 million tons of coal. 25 million tons were exported through the port of Cardiff alone.
The  number of men employed in the coal mining industry in South Wales  peaked at  271,000 in 1920.
When the coal industry was nationalised  on 1 January 1947 there were still 135 collieries with over 250 workers each .
By the time of the Strike in 1984 there were 31 pits employing 22,000 men.