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
Sussex in the High Middle Ages Essex and Kent, Sussex received some of the most migrants from what is now France after the Norman conquest. Sussex's population in 1086 has been estimated at about 66,000, doubling to 123,000 by 1290. In the High Middle Ages, the Sussex coast was one of the most densely populated parts of England. At the time of the Domesday Book in 1086 coastal Sussex and parts of Suffolk and Norfolk were the only parts of England to record a population density of 20 people per square mile, twice the average for England. Coastal Sussex remained amongst the most densely populated areas