Northumberland role in the Industrial Revolution from the 18th century on. Many coal mines operated in Northumberland until the widespread closures in the 1970s and 1980s. Collieries operated at Ashington, Bedlington, Blyth, Choppington, Netherton, Ellington and Pegswood. The region's coalfields fuelled industrial expansion in other areas of Britain, and the need to transport the coal from the collieries to the Tyne led to the development of the first railways. Shipbuilding and armaments manufacture were other important industries before the deindustrialisation of the 1980s. Northumberland remains largely rural, and is the least-densely populated county in England. In recent years the county has
Coös County, New Hampshire line, and US Route 3, which runs from Carroll in the south to the Canada–US border at Pittsburg/Chartierville, where it continues as Quebec Route 257. Coös County is the least populated of all New Hampshire counties, and the only one with significant amounts of unincorporated land; over half of the municipal-like entities are unincorporated townships, gores, or grants, a rarity in New England, where nearly all of the land is incorporated as towns or cities. The population of these unincorporated territories is minuscule; collectively they account for less than 1% of the population of the county, with only three (Wentworth's