Senedd constituencies

Establishment Following the 1997 Welsh devolution referendum, where a narrow majority voted in support of the creation of a devolved Welsh Assembly, constituencies of the devolved legislature were established. Section 2 of the Government of Wales Act 1998 stipulates that the constituencies for the National Assembly for Wales be the same as the constituencies used for elections to the United Kingdom Parliament. The same act sets out the creation of five regions which would use the same borders as the five European Parliamentary constituencies in Wales which themselves were set out in the European Parliamentary Constituencies (Wales) Order 1994, used for elections to the European Parliament between 1994 and 1999. The electoral regions set out are still used, despite the abolishment of the five European Parliamentary constituencies for an all-Wales constituency, and the withdrawal of the UK from the European Union. Although minor border adjustments to the regions have taken place. 2007 change in boundaries In 2006, the Government of Wales Act 2006 was enacted. When enacted the act reinforced the link between Assembly and UK Parliamentary constituencies, and that the number of electoral regions is five. Following the fifth periodic review of Westminster constituencies, new borders for the constituencies and electoral regions were defined by the Parliamentary Constituencies and Assembly Electoral Regions (Wales) Order 2006. This details that any further changes to the UK Parliament constituencies in Wales specified in the act (notably the proposed reduction in constituencies to 30) will not be applied to Assembly (Senedd) constituencies. In a session of the House of Commons where the then secretary of state for Wales, Cheryl Gillan was questioned on the Labour party's opposition to the decoupling of the two constituencies, she replied: Boundaries of Senedd constituencies and electoral regions were initially not overseen by any statutory review body, following the delinking of Senedd and UK Parliament constituencies in 2011. With the responsibility for proposing alterations to the boundaries of UK Parliament constituencies in Wales, and reporting to the UK Government, lay with the Boundary Commission for Wales. At the time, both constituencies had the same boundaries. Organisations such as the Electoral Reform Society Cymru indicated a preference for coterminosity (mirroring Senedd and UK Parliament constituencies, especially during the 2016 proposed reforms). However, such coterminosity was merely desired and was not enforced by law, meaning any changes to UK Parliament constituencies in Wales did not need to be mirrored for Senedd constituencies. The 2023 review of Westminster constituencies reduced the number of UK Parliament constituencies in Wales from 40 to 32, and were used from the 2024 UK election. While the Senedd is to introduce larger constituencies composed of pairings of the 32 from 2026. 2020 renaming On 6 May 2020, the Senedd and Elections (Wales) Act 2020 came into force, renaming the Assembly constituencies and Assembly electoral regions of the National Assembly for Wales, to the Senedd constituencies and Senedd electoral regions of "Senedd Cymru" or "the Welsh Parliament", known in both Welsh and English as the Senedd. 2024–25 boundary review The Senedd Cymru (Members and Elections) Act 2024, passed by the Senedd in May 2024, gave the responsibility for conducting boundary reviews of Senedd constituencies to the Democracy and Boundary Commission Cymru. The commission would be responsible to conduct reviews for specifically both the 2026 Senedd election and the 2030 Senedd election, as well as regular reviews thereafter. The 2026 review was time-constricted, The Senedd Cymru (Members and Elections) Act 2024 legislated that the 2026 election should use 16 six-member constituencies, replacing the existing 40 constituencies and five regions, with the Democracy and Boundary Commission Cymru conducting the review. The law set out that they must be contiguous pairings of the 32 UK Parliament constituencies used in Wales since 2024, and to only use a single name in both Welsh and English, unless it could be considered unacceptable for a single name. The review commenced in July 2024, with initial proposals revealed in September 2024, In March 2025, the commission published its final determinations, for the 16 constituencies (see ). The original initial proposal boundaries were re-adopted, while all constituencies were made to use Welsh-only names, with a reiteration of both support and opposition from Cymdeithas and Davies respectively, as well as consultation respondents. == Multi-member constituencies (from 2026) ==

The following is a list of the constituencies set to be used under the multi-member system from the 2026 Senedd election. All constituencies are named in Welsh only and each constituency will have six members. == Additional Member System (1999–2026) ==

Under the Additional Member System in place until May 2026, there are forty single-member constituencies and five four-member regions. The five electoral regions are: Mid and West Wales, North Wales, South Wales Central, South Wales East, and South Wales West; each region roughly contains 500,000 people and each constituency contains a population of around 60,000. The forty constituencies are listed below. The final election under the Additional Member System was the 2025 Caerphilly by-election and the final general election was the 2021 Senedd election, with boundaries that were also used for the Assembly elections of 2007, 2011, and 2016. Senedd constituencies are grouped into electoral regions consisting of between seven and nine constituencies. An additional member system is used to elect four additional Members of the Senedd from each region, in addition to the MSs elected by the constituencies. The Electoral Regions boundaries were based upon the pre-1999 European Parliament constituencies. At each general election of the Senedd, each elector had two votes, one constituency vote and one regional party-list vote. Each constituency elected one Member by the first past the post (single-member district plurality, SMDP) system, and the additional Senedd seats were filled from regional closed party lists, under the D'Hondt method, with constituency results being taken into account, to produce a degree of proportional representation for each region. Altogether, the sixty Members of the Senedd were elected from the forty constituencies and five electoral regions, creating a Senedd of forty constituency MSs and twenty additional MSs, with every constituent represented by one constituency member and four regional members. The constituencies were the same as those used for elections to the House of Commons of the United Kingdom until the 2024 United Kingdom general election but not linked to them. The borders of each constituency were drawn using Local government boundaries, defined in Parliamentary Voting System and Constituencies Act 2011 as "the boundaries of counties, county boroughs, electoral divisions, communities and community wards". 2007–2026 Constituencies 1999–2007 constituencies Between the first election in 1999 for the then National Assembly for Wales, to the 2007 election, there were three former constituencies. These constituencies were replaced at the 2007 election, with new boundaries and names. Three constituency names, Conwy, Caernarfon, and Meirionydd Nant Conwy, became historic, and the new boundaries defined three constituencies with new names: Arfon, Dwyfor Meirionnydd, and Aberconwy. Generally, the new boundaries define each constituency taking into account local government ward boundaries, and define constituencies close to equal in terms of the sizes of their electorates. Former electoral regions == See also ==