2001 Census geographies

Output Areas (OAs) are the lowest level of geographical area for census statistics. They are made up of between 40 and 250 households and have a usually resident population between 100 and 625 persons. There are some exceptions where OAs may have more than 625 people, for example, where there is a large prison.

OAs are based on census records for addresses that have the same postcode. They were created where possible to fit within the 2003 statistical ward and parish boundaries. If a postcode contained addresses that were split between an electoral ward, division or parish boundary, this meant that different addresses with the same postcode could be split between two or more OAs.

There were 165,665 OAs in England and 9,769 in Wales.

Lower layer Super Output Areas (LSOAs) are made up of groups of OAs, usually four or five. They comprise between 400 and 1,200 households and have a usually resident population between 1,000 and 3,000 persons.

There were 32,482 LSOAs in England and 1,896 in Wales. View and download the names and codes of LSOAs on our Open Geography website.

Middle layer Super Output Areas (MSOAs) are made up of groups of LSOAs, usually four or five. They comprise between 2,000 and 6,000 households and have a usually resident population between 5,000 and 15,000 persons. MSOAs fit within local authorities.

There were 6,781 MSOAs in England and 413 in Wales. View and download the names and codes of LSOAs on our Open Geography website.

OAs, LSOAs and MSOAs make up the different levels of census statistical geographies.

Wards can refer to either:

• local authority electoral wards

• Census Area Statistics (CAS) wards (created by us)

• statistical wards (created by us)

Census outputs for most electoral wards are included with the outputs for 2003 CAS wards and 2003 statistical wards.

2003 CAS wards are similar to 2003 statistical wards. The only difference is that 18 of the smallest statistical wards (all in England) were merged into 7 other wards, to create CAS wards. This was to keep the information about individuals, households and organisations in these areas confidential.

There were 7,969 CAS wards in England and 881 in Wales.

2003 statistical wards reflect the ward boundaries on 31 December 2002. Most 2003 statistical wards are the same as electoral wards as of May 2003. Although for some local authorities, the 2003 statistical ward list is different to the 2003 electoral ward list. This is because of ward boundary changes that did not start until May 2004. View and download the names and codes of CAS wards used in the 2001 Census on our Open Geography website.

Civil parishes are mainly found in rural areas in England. In Wales they are known as “communities” and cover the whole of the country. Councillors are elected to a parish council and carry out powers and duties set out in legislation.

There were 10,387 parishes in England and 866 communities in Wales.

A Travel To Work Area is an area where a large proportion of workers both live and work.

In 2001 there were 243 Travel To Work Areas covering the UK.

They are based on groups of Lower layer Super Output Areas (LSOAs) in England and Wales, Data Zones in Scotland and Super Output Areas in Northern Ireland.

Some areas may cross country borders. Where this occurs, they could either be an area that covers parts of England and Wales, or an area that covers parts of England and Scotland.

View and download the names and codes of Travel To Work Areas used in the 2001 Census on our Open Geography website.

Find out about the different geographies used in Scotland’s 2001 Census on Scotland’s Census website.

Find out about the different geographies used in Northern Ireland’s 2001 Census on the Northern Ireland Statistics and Research Agency (NISRA) website.