The A580 (officially the Liverpool–East Lancashire Road, colloquially the East Lancs) is the United Kingdom's first purpose-built A road. The road was officially opened by King George V on 18 July 1934. Despite its name, the actual road runs through the modern day metropolitan counties of Merseyside and Greater Manchester which were historically in Lancashire when the road was built until 1974. Notable towns and cities along the route include Liverpool, Kirkby, St. Helens, Leigh, Swinton and Salford. It was described as "Britain's biggest road" at the time.

The road was built to provide better access between the Port of Liverpool and the industrial areas of East Lancashire around Manchester. The new high-quality trunk road would supersede the indirect and heavily built-up A57 through Prescot, Warrington and Eccles. Journey times for road haulage would be reduced to under an hour.

This road was built with a 1930s Dutch-style cycle path running its entire length. Many roads at this time were built with cycle paths but most have been lost due to road widening schemes.

The first part, which was completed within three years, was from Walton, Liverpool, to the junction with the A6 at Irlams o' th' Height in Salford. The 29.5-mile (47.5 km) road was constructed in an almost straight alignment with few curves.

To be a high-speed trunk route, its 1930s planners designed some parts to be three roads in one. The central section was exclusively for through traffic while adjacent side roads – either side of the main carriageway – provided local access. Although the sections within Liverpool were dual carriageway from the beginning, a few short stretches through Salford continue to use the original three-lane layout. The rest of the road was converted to dual with a central reservation in the 1950s and 1960s. Many of the original 1930s bridges remain; they were built from steel in preparation for any future expansion as they would be easier to replace than ones constructed from moulded concrete.

The road remains the UK's largest pre-motorway project. In 2004 the Highways Agency detrunked the road, passing control and maintenance over to the local authorities along its route.

With the completion of the first phase, the next stage was to extend the road beyond Salford and into East Lancashire proper. However this was never undertaken. Its failure was largely due to the road's location. Despite linking North West England's largest cities, the East Lancs remained isolated from the rest of the UK's national road network. Both ends of the highway began in high-density urban areas that were not close to any comparable infrastructure that could assist rapid transit connections.

By 1942, proposals were put forward to extend the A580 across the Pennines to Hull on the east coast of Britain. Although this plan never came to fruition, its purpose became the foundation for the construction of the M62 motorway in 1960.

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  View from the bridge on the A580 slip road
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  A580 bridge over Croxteth Brook 3.jpg

• Lancashire Motorway & Roads Site

53°28′15″N 2°36′54″W / 53.4707°N 2.6149°W / 53.4707; -2.6149

• http://www.bikeboom.info/1930s/