Census Geography: Wales 1991

The 1991 census geography hierarchy in Wales is based on the smallest areal units known as "Enumeration Districts" (EDs). These were the areas which formed the responsibility of a single census enumerator. They were designed by census planners drawing boundaries by hand onto photocopied Ordnance Survey maps and were subsequently digitised. The 6,600 Welsh 1991 EDs contain an average of 412 persons and 167 households. The minimum threshold for publication of census data was 50 persons and 25 households although some EDs were created that contained smaller populations, and the data for these "restricted EDs" was combined with that of another nearby ED. There is no clear relationship between ED and postcode boundaries because they were created by completely separate processes.

EDs nest within wards as of 21 April 1991, the date of the census. Wards vary widely in population size, but tend to be of similar population sizes within a single local government area. The census area coding included one additional "shipping ward" within each local authority, which does not relate to a true geographical area but was included for the purpose of recording individuals enumerated on board ships. These wards always have a code of "SS". The local government tier comprises local authority districts. The district level nests within the county level and this is reflected in the coding of the census areas. The codes for these different levels are combined to create an 8-character alphanumeric code. Area names are applied to all levels about the ED. This census geography coding scheme will be found within postcode directories and census datasets.

Digital boundary data are available for all units in the hierarchy but registration is required.

Example