<P> The Liverpool Built - up Area (previously Liverpool Urban Area in 2001 and prior) is a term used by the Office for National Statistics (ONS) to denote the urban area around Liverpool in England, to the east of the River Mersey . The contiguous built - up area extends beyond the area administered by Liverpool City Council into adjoining local authority areas, particularly parts of Sefton and Knowsley . As defined by ONS, the area extends as far east as Haydock, and Ashton - in - Makerfield in Greater Manchester . </P> <P> The Liverpool Urban Area is not the same area as Merseyside (or Greater Merseyside), which includes areas of Wirral on the west bank of the Mersey and Southport. . The western extent of the Greater Manchester conurbation is narrowly avoided as that extends as far as Golborne and Newton - le - Willows, with small gaps separating those towns from Ashton - In - Makerfield and Haydock . </P> <P> The Liverpool Urban Area defined by ONS covers Liverpool and its contiguous built - up areas, with a population of 864,122 a considerable increase from the 2001 census due to the rapid growth in the population of Liverpool during this period . The population of the area was 816,216 in the 2001 census, . The urban area facing Liverpool on the Wirral Peninsula is a separate division known as the Birkenhead Urban Area . </P> <P> The ONS definition is based purely on physical criteria with a focus on the presence or absence of significant gaps between built - up areas . It therefore extends as far as Ashton - in - Makerfield, but excludes some areas much closer to Liverpool which are separated from it by open spaces, notably Kirkby with a narrow gap along the M57 motorway, and Maghull . </P>

Why did liverpool grow as an urban area
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