Coal has been mined in New South Wales for nearly 200 years and prior to 1970 the vast majority of this coal was mined from underground mines using bord and pillar or similar systems. Since 1970 there have been two notable changes in coal production trends in New South Wales as can be seen from Figure 1.
1. The steady growth in coal mined by open cut methods. Open cut output grew from about seven per cent of the State's output in 1970/71 to 43 per cent in 1990/91.
2. The steady growth in coal mined by the longwall method. longwall output grew from negligible amounts in 1970/71 to 48 per cent of underground production in 1990/91. mines operating longwall units produced 61 per cent of underground production in 1990/91.