Census Geography: Wales 1971

The smallest areal units of the 1971 census geography hierarchy in Wales are "Enumeration Districts" (EDs). These areas were each the responsibility of a single census enumerator. These EDs were designed entirely manually and no contemporary digital boundaries exist. The 6,457 Welsh 1971 EDs contain an average of 423 persons and 139 households. The minimum threshold for publication of census data was 25 persons and 8 households. There is no clear relationship between ED and postcode geography because they were created by completely separate processes and no national lists of postcode geography were available in 1971.

EDs nest within wards. 1971 wards have a mean size of 2,047 persons or 675 households. There are two local government tiers comprising 168 councils at the local authority level (variously, urban and rural districts, county and metropolitan boroughs) and a higher level of 13 counties. 1974 saw a major reorganization of local government in the UK affecting both of these levels which means that it can be difficult to exactly match 1971 data to the post-1974 structures. Area names are used at the county, local authority and ward levels, but EDs have only numbers. Each local authority contained one "shipping" ED within one "shipping" ward for the allocation of residents aboard British-registered shipping at the time of the census, although for most local authorities the population of the shipping ward is 0. Different area coding schemes are in use for the remaining sources of access to the 1971 census data and it is not possible to definitively describe the codes that may be encountered. It is therefore essential to ensure that when using 1971 census data, an appropriate area code list is used to translate between codes and area names.

In addition to the ED geography, 1971 census data were assigned grid references and aggregated to 1km x 1km grid squares, providing an alternative geographical representation of the census data. These grid square data formed the basis for the maps in the publication People in Britain: A Census Atlas (CRU/OPCS/GROS, 1980). Following the 1981 census, a 1971-81 change file was published, which identified the relationship between 1971 and 1981 EDs in terms of "tracts" which were aggregations of 1971 and 1981 EDs whose external boundaries were comparable between the two censuses. 48,300 such areas were identified in England and Wales, in addition to 10,700 parishes or communities, mostly in rural areas, which remained largely unchanged between the censuses.

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