Historic counties of Wales
The historic counties of Wales (Welsh: siroedd hynafol) are  sub-divisions of Wales. They were used for various functions for several hundred years, but for administrative purposes have been superseded by contemporary sub-national divisions, some of which bear some limited similarity to the historic entities in name and extent. They are alternatively known as ancient counties. The counties

 

1 The earldom of Pembroke and lordship of Glamorgan pre-date the Edwardian conquest. 2 These counties originate in 1282, following King Edward I's conquest. 3 These counties originate in 1535, with the Laws in Wales Act, 1535, converting the remaining Marcher Lordships into counties. 4 Despite being created at the same Act as the other counties, Monmouthshire was included with English counties for legal purposes until 1974. Between 1536 and 1974 the formulation "Wales and Monmouthshire" was frequently used. The 1535 Laws in Wales Act had the effect of abolishing the marcher lordships within and on the borders of Wales. In the border areas, several were incorporated in whole or in part into English counties. The lordships of Ludlow, Clun, Caus and part of Montgomery were incorporated into Shropshire; and Wigmore, Huntington, Clifford and most of Ewyas were included in Herefordshire. The historic counties established by 1535 were used as the geographical basis for the administrative counties, governed by county councils, which existed from 1889 to 1974. The historian William Rees said, in his "Historical Atlas of Wales": (published 1959)
"... the boundaries of the modern shires have largely been determined by the ancient divisions of the country. The survival of these ancient local divisions within the pattern of historical change constitutes a vital element in the framework of the national life and helps to preserve its continuity." Four circuits of Wales
In the 1536 acts of the Union, a Court of Great Sessions in Wales was created in Wales for four separate circuits. The circuits each had 3 counties involved. Some of the original territorial Marcher lordships were split into regional circuits and others were created from regions of the former Principality of Wales:

Anglesey, Caernarfon & Merioneth
Flint, Denbigh & Montgomery
Cardigan, Carmarthen & Pembroke
Radnor, Brecon & Glamorgan

Exclaves
The Counties (Detached Parts) Act 1844 abolished several enclaves. One of these, Welsh Bicknor (Llangystennin) was an exclave of Monmouthshire between Gloucestershire and Herefordshire and was transferred to Herefordshire. Two townships of the ancient parish of Cwmyoy were also exclaves of Herefordshire. Bwlch Trewyn was transferred to Monmouthshire, whereas the other, Ffwddog (identified using the English variant Fothock on older maps), was not. The Herefordshire township of Litton and Cascob (in the parishes of Cascob and Presteigne), was transferred to Radnorshire. The Denbighshire township of Carreghofa (in the parish of Llanymynech) was transferred to Montgomeryshire. The exclaves of Flintshire, called English Maelor and Marford and Hoseley were left untouched. Monmouthshire

The territory which became Monmouthshire was part of the Welsh kingdoms of Gwent and Glywysing and later, after the Norman conquest of southern Wales, of the Welsh Marches. Although the original Laws in Wales Act of 1535 specifically stated the lands making up Monmouthshire were from the 'Country or Dominion of Wales', the Laws in Wales Act 1542 added Monmouthshire to the Oxford circuit of the English Assizes rather than falling under the Court of Great Sessions in Wales. According to historian John Davies, this arrangement was the cause of the erroneous belief that the county had been annexed by England rather than remaining part of Wales. In later centuries, some English historians, map-makers, landowners and politicians took the view that Monmouthshire was an English rather than a Welsh county, and references were often made in legislation to "Wales and Monmouthshire". The position was finally resolved by the Local Government Act 1972, which confirmed Monmouthshire's place within Wales. Local government

1889
The Local Government Act 1888 created a parallel system of administrative counties based on the historic counties in 1889. Additionally, certain boroughs were deemed to be county boroughs, outside the administrative counties (Cardiff and Swansea in 1889, Newport in 1891 and Merthyr Tydfil in 1908). As a result of 85 years of local government boundary changes, the boundaries of the administrative counties became increasingly different from the historic counties, until they were abandoned altogether for a different system of local government in 1974. 1974
The Local Government Act 1972 replaced the administrative counties created in 1889 with eight new administrative counties in 1974. The existing Lieutenancy areas were also redefined to use the newly created local government areas, defined by the act as "counties." Furthermore, use of the historic counties as postal counties was stopped by the Royal Mail in 1975 and those historic counties were no longer shown on maps. However, in spite of widespread misunderstanding, the Local Government Act 1972 never abolished the historic counties. Indeed, the Department of the Environment made this very clear in a statement it issued on 1 April 1974:

"  The new county boundaries are solely for the purpose of defining areas of...local government. They are administrative areas, and will not alter the traditional areas of Counties (the historic counties), nor is it intended that the loyalties of people living in them will change." The eight new administrative counties were themselves replaced in 1996 by the current principal areas of Wales, but modified versions were retained for Lieutenancy as the preserved counties. Vice counties
The vice counties, used for biological recording throughout Great Britain and Ireland since 1852, are largely based on historic county boundaries. They ignore all exclaves and are modified by subdividing large counties and merging smaller areas into neighbouring counties. The static boundaries make longitudinal study of biodiversity easier. Index of Place Names
The historic counties of Wales are included in the Index of Place Names (IPN) published by the Office for National Statistics. Each "place" included in the IPN is related to the historic county it lies within, as well as to a set of administrative areas. The Historic Counties Trust has published demographic statistics for the historic counties of the UK from the 2011 United Kingdom census including a comparison of population and population density in the historic counties of England and Wales between the 1901 United Kingdom census   and the 2011 United Kingdom census  and a comparison of the number of Welsh speakers in the historic counties of Wales between the 1911 United Kingdom census   and the 2011 United Kingdom census. References

External links
The Historic Counties Trust
Campaign for Historic Counties
Interactive map of the historic counties
Family history links to historic counties of Wales

 
Wales
Counties Wales
Lists of counties of Wales