The land on which Spennymoor now stands was once a huge expanse of moorland. Modern Spennymoor was built on mining, starting with the sinking of the Wittered pit in 1839. Industrial development came quickly and in 1853 the Weardale Iron and Coal Company opened its ironworks at Tudhoe. Workers came from across the country to work in the coal and iron industries. The town grew in prosperity in to the twentieth century.
The closure of the ironworks at Tudhoe in 1901 was the first sign of industrial decline in the area. After the decline of mining in the twentieth century new manufacturing industries were established. New investment in the area was highlighted in 1968 when the Tudhoe ironworks site was developed to provide 1009 new houses for workers in the new factories.