Large areas of many northern cities in the United States experienced population decreases and a degradation of urban areas. Inner-city property values declined, and economically disadvantaged populations moved in. In the U.S., the new inner-city poor were often African-Americans that migrated from the South in the 1920s and 1930s. As they moved into traditional white neighborhoods, ethnic frictions served to accelerate flight to the suburbs. United Kingdom Like many industrial nations before the Second World War, the United Kingdom carried out extensive slum clearances. These efforts continued after the war, however in many of these slums, depopulation became common, producing compounding decay. The UK is unlike much of Europe in having high overall population density, but low urban population density outside of London. In London, many former slum neighbourhoods like in Islington became "highly prized," however this was the exception to the rule, and much of the north of England remains deprived. The Joseph Rowntree Foundation in the 1980s and 90s undertook extensive studies culminating with a 1991 report which analyzed the 20 most difficult council estates. Many of the most unpopular estates were in East London, Newcastle upon Tyne, Greater Manchester, Glasgow, the South Wales valleys, and Liverpool, their unpopularity driven by a variety of causes from the loss of key industries, population decline, and counterurbanization. Population decline in particular was noted to be faster in inner city areas than in outer ones, however a decline was noted throughout the 1970s, 80s, and 90s in both inner and outer city areas. Jobs declined between 1984 and 1991 (a decline observed particularly among men), while outer areas saw job growth (particularly among women). The UK also saw urban areas become more ethnically diverse, however urban decline was not limited to areas which saw population changes. Manchester in 1991 had a non-white population 7.5% higher than the national average, but Newcastle had a 1% smaller non-white population. Features of British urban decay analyzed by the Foundation included empty houses; widespread demolitions; declining property values; and low demand for all property types, neighborhoods, and tenures. Urban decay has been found by the Foundation to be "more extreme and therefore more visible" in the north of the United Kingdom. They note this trend of northern decline has been observed not just in the United Kingdom but also in much of Europe. Some seaside resort towns have also experienced urban decay towards the end