In the intervening years, the Hodbarrow iron mines began extracting haematite from deposits between the village of Holborn Hill and the seashore at Hodbarrow. The first shafts were sunk in the 1850s, by 1881 there were seven pits operated by the Hodbarrow Mining Company. Millom & Askam Iron Company built Millom Ironworks and the first furnaces were completed in 1866. The opening of the ironworks led to the building of Millom newtown. The Hodbarrow Outer Barrier (seawall) was completed in 1905 to protect the mines from the sea. It took five years to construct at a cost of almost £600,000. The Hodbarrow Mines and Millom Ironworks were closed in 1968. The town's population of 10,997 in 1967 fell to 7,101 by the 1971 census.