The preserved counties were originally almost identical to the 1974–96 counties, but with a few minor changes in line with local government boundary changes:
Llanrhaeadr-ym-Mochnant,
Llansilin and
Llangedwyn were transferred from
Clwyd to
Powys, and
Wick,
St Brides Major,
Ewenny and
Pentyrch were transferred from
Mid Glamorgan to
South Glamorgan. There were however two local government areas,
Caerphilly and
Conwy, split between preserved counties. The Local Government Boundary Commission for Wales were instructed by the
National Assembly for Wales on 11 March 2002 to undertake a review of preserved county boundaries. In their final proposals the part of the local government area of
Caerphilly which had been in Mid Glamorgan was to be part of Gwent and the part of the local government area of
Conwy which had been in
Gwynedd was to be part of
Clwyd. The boundary between Mid Glamorgan and South Glamorgan was also to be re-aligned to reflect small changes in local government boundaries. The Assembly accepted these proposals such that from 2 April 2003 each preserved county encompassed between one and five whole local government areas. The boundary between West Glamorgan and Powys was further modified on 1 April 2005 as a result of boundary changes between Ystalyfera and Ystradgynlais. The boundary between Mid Glamorgan and Powys was further modified on 1 April 2010 to reflect the 2009 local government boundary changes in the area around
Vaynor,
Merthyr Tydfil. ==List==