Sunderland needed a bigger bridge by the 1920s. The old cast-iron crossing was elegant and Pevsner had praised it, but motor traffic had grown beyond what it could carry, and the design was reaching the end of its second century. Mott, Hay and Anderson - one of the great consulting engineering firms of the era - designed a through-arch in steel, with the deck suspended below an arch that rises overhead. Sir William Arrol's Glasgow yard fabricated the components. The construction trick was to assemble the new bridge around the existing one so that the river crossing remained open. Sunderland never lost its bridge: it acquired a new one and dismantled the older bridge from within. The total cost came to £231,943, of which £12,000 went on demolishing the predecessor.

The Duke of York opened the bridge on 31 October 1929. He would later become George VI - the wartime king of Britain's darkest hour, whose stammer Colin Firth made famous decades later in The King's Speech. In October 1929 he was the second son of George V, not yet expected to inherit, performing the kind of civic duty that Royal princes performed several times a week in the era. The new bridge was substantial: a steel arch large enough to carry the A183 between Chester-le-Street and South Shields and the A1018 - the original route of the A19 before the bypass was built leading to the Tyne Tunnel. The bridge became Grade II listed, and the form has not changed since. The arch overhead still defines the view downriver from the city centre.

For most of its life the Wearmouth Bridge has been a quietly busy crossing. On matchdays at the Stadium of Light, just upstream on the north bank, the traffic concentrates - tens of thousands of fans crossing to reach the ground. Sunderland City Council commissioned the Keel Crossing in 2023, a new pedestrian and cyclist bridge linking the Vaux site and the south bank to Sheepfolds and the Stadium of Light. The crossing opened to its full length in September 2024 and permanently in October 2025, easing the matchday congestion on the older bridge. The two structures now share the crossing function - the Wearmouth Bridge for road traffic, the Keel Crossing for fans on foot - and the older bridge gets to do less in exchange for a longer life.

Sunderland AFC redesigned its club crest in 1997, the year the Stadium of Light opened. The new crest carried two silhouettes from the local skyline: the Penshaw Monument standing on its hill to the south-west, and the Wearmouth Bridge arching across the river. Football crests are usually conservative things - lions, castles, dates - but Sunderland chose to put the working infrastructure of its city on the badge. The bridge silhouette on the shirt every match day is the same arch that George VI opened in his Duke of York years, the same steel that Glasgow's Dalmarnock Ironworks shipped down by rail in 1928. Sunderland's idea of itself runs through that bridge. Most cities would settle for the cathedral. Sunderland chose the place where its road becomes its river.