A74(M) and M74 motorways

The A74 was the original route from Glasgow to Carlisle, where it met the A7 in Carlisle city centre and the A6 south to London.

Starting in the 1930s, the single-carriageway road between Gretna and Glasgow was progressively upgraded to dual carriageway, being completed in the early 1970s with the completion of the Gretna bypass.

At the northern end, it was not possible simply to add to the existing carriageway because of the built-up nature of the area. A bypass was built as one of Scotland's first motorways, the M74, from Draffan to Maryville, north of Uddingston, completed by 1969.[3] Junctions were originally numbered from south to north, which was the normal convention at the time numbers increasing going away from London, as there were no plans to extend the motorway.

The northern section around Hamilton was built as three-lane dual carriageway, narrowing to two-lane dual carriageway south of junction 4. It continued as the A74 Dual-Carriageway from Draffan and carrying on to link with the M6 junction 44 at Carlisle.

The southern sections, where there was no need to bypass the existing route, were not originally upgraded to motorway standard, but to dual carriageway without hard shoulders or full grade separation. The gradual construction of the M6 from Rugby (where it met the M1 to London) to Carlisle in 1970, where it terminated on the A74, meant that the route from Glasgow to London was entirely dual carriageway.

This led to calls for the already dualled A74 from Draffan to the M6 to be upgraded a second time, to motorway standard. As the government had already invested in the dual carriageway upgrade, they initially resisted these calls. In 1972 the Government agreed to extend the M74 from Draffan to today's J12 at Millbank. It was built in three sections, opening 1986–87. It was constructed to dual two-lane standard, and included a bypass of Lesmahagow, as the M74.

In 1984, in preparation for the southwards extension, the junction numbers were changed to go from north to south, Raith (junction 5) on the original south to north numbering remained as junction 5, with Maryville (the most northerly junction at that time) becoming junction 4, leaving lesser numbers available for junctions for the expected continuation of the motorway northwards.

When the first southern extension opened, Draffan, originally junction 1, ceased to exist and junction 9 (the first junction on the new extension) was and still is only a southbound exit onto the old A74 just south of Blackwood village, to serve the villages of Blackwood, Kirkmuirhill, Lesmahagow and Coalburn.

In 1987, the government committed to upgrading the remaining A74 from J12 to the M6 to motorway standard. When the first section opened, as far south as Abington (J12-J13) in 1991 it was numbered M74. Following this, the government announced that the route would be completed as the M6, as the two motorways would meet head on at Carlisle. The Scottish section of the A74 was then upgraded in sections, not all contiguous, as the A74(M), a temporary number until all the sections were complete, and the eight-mile (13 km) English section had been constructed and connected to the M6. They were constructed with dual three-lane carriageways. In 1995 the first northern extension was opened to Fullerton Road in Glasgow, as M74. The A74 upgrades were complete by 1999.

Plans to upgrade the English section of A74 (Cumberland Gap) from the Scottish border at Gretna to Carlisle[4] were announced in 2004. Costing £174m, this was constructed as M6 as originally planned in the 1990s, and was opened on 5 December 2008.[5] The project also included the construction of a new bridge crossing the River Esk.[6] This means that there is now a continuous motorway from London to Glasgow, with four numbers (M1, M6, A74(M) and M74).

Construction on the six-lane M74 Northern Extension (M74 Completion) northwards by 5 miles (8.0 km) through the south-eastern part of Glasgow to meet the M8 started in 2008,[7] with opening on 28 June 2011.[8] The extension involved the demolition of the Rosebery Park football ground.[9]

The city centre section is supposed to perform a similar role to the never-built southern flank of the Glasgow Inner Ring Road planned in the 1960s, and first set out as a scheme in the Bruce Report of the 1940s, but only half-completed. The scheme was at the centre of a road protest from local campaigners and environmentalists; their appeal against the road orders collapsed in June 2006. Scottish First Minister Alex Salmond officially launched construction on 28 May 2008.[10]

Archaeological mitigation was required as part of the project and was one of the largest coordinated series of excavations carried out in an industrial city in Western Europe. Due to the sheer size of the project a joint venture by Headland Archaeology and Pre-Construct Archaeology were responsible for the excavations in 2007 and 2008;[11] during this time eight large former industrial sites were investigated involving more than a hundred archaeologists. Discoveries included the Govan Iron Works and associated workers' housing, the Caledonian Pottery, a block of 19th century tenements, a biscuit factory, urban limeworks and more. Many of the structures were in use into the 20th century. The excavation of both manufacturing and domestic sites provided a unique insight into both how objects were made and how they were used. Finds included stamped bricks from three local manufacturers, bottle and window glass fragments, and pottery stamps or transfer prints with different customer names on them.[12]

The motorway construction, initially expected to cost £445 million, ran under-budget at £437 million. The project total is estimated to be £692 million once the cost of purchasing land is included.[13] There was a £12 million allowance for grouting of old mine workings.[14]

Road sign on the A702 showing the change in designation.

Construction of the East End Regeneration Route (designated as the A728) made use of existing stretches of road and filler sections on previously derelict land and has the ultimate intention to connect the M74 Northern Extensions with the M8 motorway at the Provan Gas Works interchange with the M80 motorway. Phase 1 and Phase 2 from the M74 Junction 1A (Polmadie) to the A89 west of Parkhead began in 2008 and was completed in 2012, but Phase 3 from Parkhead to the M80 did not follow as planned.[15][16] Although plans were approved in early 2016, construction did not commence;[17][18] in 2021, it was confirmed that the project was still under consideration by the council despite funding problems and opposition on environmental grounds.[19]

A new sculpture is planned near Gretna called the Star of Caledonia. One intention is for it to be viewed from the motorway, although there will be no motorway signs to indicate the structure.[20]

• Northern extension
• Southern extension
• Public Inquiry findings

Wikimedia Commons has media related to M74 motorway.

• JAM74: Joint Action against the M74
• Friends of the Earth: Stop Motorway Madness
• The Motorway Archive – M74/A74(M)
• BBC NEWS | UK | Scotland | Glasgow, Lanarkshire and West | Final go-ahead for M74 extension
• M74-M8 Interchange – Clyde Waterfront regeneration