The A48 is a major trunk road

Trunk road

A trunk road, trunk highway, or strategic road is a major road—usually connecting two or more cities, ports, airports, and other things.—which is the recommended route for long-distance and freight traffic...

 in Great Britain

Great Britain

Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

. It runs from the A40

A40 road

The A40 is a major trunk road connecting London to Fishguard, Wales and officially called The London to Fishguard Trunk Road in all legal documents and Acts...

 at Highnam

Highnam

Highnam is a village and civil parish on the outskirts of the city of Gloucester. It is three miles northwest of the city on the A40, on its way to Ross, west of Alney Island and Over Bridge. The parish includes the villages of Lassington and Over...

 3 miles (4.8 km) west of Gloucester

Gloucester

Gloucester is a city, district and county town of Gloucestershire in the South West region of England. Gloucester lies close to the Welsh border, and on the River Severn, approximately north-east of Bristol, and south-southwest of Birmingham....

 to the A40 at Carmarthen

Carmarthen

Carmarthen is a community in, and the county town of, Carmarthenshire, Wales. It is sited on the River Towy north of its mouth at Carmarthen Bay. In 2001, the population was 14,648....

. Before the construction of the M4 motorway

M4 motorway

The M4 motorway links London with South Wales. It is part of the unsigned European route E30. Other major places directly accessible from M4 junctions are Reading, Swindon, Bristol, Newport, Cardiff and Swansea...

 and the first Severn Bridge

Severn Bridge

The Severn Bridge is a suspension bridge spanning the River Severn between South Gloucestershire, just north of Bristol, England, and Monmouthshire in South Wales, via Beachley, a peninsula between the River Severn and River Wye estuary. It is the original Severn road crossing between England and...

 in the mid 1960s it was the principal route into South Wales

South Wales

South Wales is an area of Wales bordered by England and the Bristol Channel to the east and south, and Mid Wales and West Wales to the north and west. The most densely populated region in the south-west of the United Kingdom, it is home to around 2.1 million people and includes the capital city of...

. For most of its journey through Wales, it runs almost parallel to its successor. Before the construction of the Second Severn Crossing

Second Severn Crossing

The Second Severn Crossing is a bridge which carries the M4 motorway over the River Severn between England and Wales, inaugurated on 5 June 1996 by HRH The Prince of Wales to augment the traffic capacity of the original Severn Bridge built in 1966...

, during times of high winds at the Severn Bridge the A48 was used as part of the diversion route, and is still marked as a Holiday Route.

From Gloucester the A48 runs through the villages of Minsterworth

Minsterworth

Minsterworth is a village in Gloucestershire, UK. It lies on the border of Gloucester, on the north bank of the River Severn and on the A48 road between Gloucester and Chepstow, at...

, Westbury-on-Severn

Westbury-on-Severn

Westbury-on-Severn is a rural village in England that is the centre of the large, rural parish, also called Westbury-on-Severn.-Location:The village is situated on the A48 road and bounded by the River Severn to the south and west.The village has a large parish church which is distinctive as the...

, connects to a link road to Cinderford

Cinderford

Cinderford is a small town on the eastern fringe of the Forest of Dean in Gloucestershire, England. A population of 8,116 people is recorded in the 2001 census....

 in the Forest of Dean

Forest of Dean

The Forest of Dean is a geographical, historical and cultural region in the western part of the county of Gloucestershire, England. The forest is a roughly triangular plateau bounded by the River Wye to the west and north, the River Severn to the south, and the City of Gloucester to the east.The...

 then through Newnham

Newnham on Severn

Newnham on Severn is a village in west Gloucestershire, England. It lies near the Royal Forest of Dean, on the west bank of the River Severn, approximately 10 miles south-west of Gloucester and three miles southeast of Cinderford, at . It is on the A48 road between Gloucester and Chepstow,...

, Blakeney

Blakeney, Gloucestershire

Blakeney is a village in Gloucestershire, England. It is the largest village in the parish of Awre. It has views of the Forest of Dean.It dates back to AD 75, and was home to Thomas Sternhold, a groom of King Henry VIII's Robes.-References:*...

 and bypassing the town of Lydney

Lydney

Lydney is a small town and civil parish in the English county of Gloucestershire. It is located on the west bank of the River Severn, close to the Forest of Dean. The town lies on the A48 road, next to the Lydney Park gardens with its Roman temple in honour of Nodens.-Transport:The Severn Railway...

 (the bypass was built in the 1990s) on the west bank of the River Severn

River Severn

The River Severn is the longest river in Great Britain, at about , but the second longest on the British Isles, behind the River Shannon. It rises at an altitude of on Plynlimon, Ceredigion near Llanidloes, Powys, in the Cambrian Mountains of mid Wales...

.