A mate of mine gave me a leaflet about this the other day. When the pits were nationalised in 1947 there were 151 working collieries in Co Durham. It makes me wonder how many men were employed in the mines in those days. There were three in my village alone. East Tanfield, Tanfield Lea & Tanfield Moor. It's interesting doing a bit research about this.
Coal production peaked in 1913 and in 1923 there were 170,000 miners working in County Durham. The industry declined in the county after the Second World War and many pits closed in the 1950s and 1960s. The last colliery in the Durham coalfield closed in 1994 Lifted from http://www.durhamrecordoffice.org.uk/article/10560/Coal-Mining-and-Durham-Collieries Seven of my Uncles worked in the Pits, Northumberland, Durham and Midlands. Four of them had the “Pittman’s disease” and have died of it. Fascinating what used to happen pre Nationalisation in a disgusting sense of that word ie what the Mine Owners used to do.
I did a lot of research a few years back because my Grandad was a pit deputy at North Walbottle. I came across this site and got so much into the history of the mines and the people who worked in them. It is very sad to see how many people lost their lives, and how young some of them were. The index at the top of the page will take you to any mine that you want to research. At the bottom of the page you will find the 'In Memoriam' index. Happy researching. http://www.dmm.org.uk/colliery/t001.htm
There's a really good interactive map at the Winter Gardens museum in Sunderland with an LED display of each colliery, and you can press 'year' buttons to see how the numbers decreased over time.