The A48 is a major trunk road in Britain. It runs from Gloucester, England to Carmarthen, Wales. From Gloucester the road passes through Blakeney and Lydney on the west bank of the River Severn. Continuing west along the South Wales coast, it connects Chepstow, Newport, Cardiff, Cowbridge, Bridgend, Port Talbot, Neath and Pontarddulais before terminating at Carmarthen.

Before the construction of the M4 motorway and Severn bridges in the mid 1960s it was the principal route into south Wales.