A bid has been launched to grant the Erskine Bridge the same A-list status as protected national landmarks.
The move by Historic Environment Scotland (HES) would see the structure ranked alongside Edinburgh Castle and Glasgow University.
The former toll bridge, which spans the River Clyde, was constructed between 1967 and 1971 at a cost of £10.5m.
It is almost a mile long (1,322m) and has a clearance height of 45m (148ft) so larger ships can pass underneath.
HES said: "The Erskine Bridge was a state-of-the-art infrastructure landmark for its time and remains one of the country's most architecturally and technically distinguished bridges of the post-war period and beyond its date of construction."
The need for a bridge to replace the old Erskine Ferry on the Clyde was established before World War Two.
But it was the 1960s before the project became a reality as part of a major investment in Scotland's motorway network.
The infrastructure scheme for the M8 and Clyde also included the Kingston Bridge and the Clyde Tunnel.
The Tay Bridge and the Forth Road Bridge were among major projects in other parts of the country.
When the Erskine Bridge was opened by Princess Anne in 1971 it had the longest cable-stayed span of its type in the world.
Part of the A898 (M898), it connects Renfrewshire with West Dunbartonshire and was a toll bridge until 2006, when the 60p charge was abolished.
It also had the highest clearance between river and roadway in Scotland until the opening of the Queensferry Crossing last year.
An HES report concluded: "On account of its unique place within the history and development of bridge engineering, category A is considered to be the most appropriate category of listing, denoting outstanding significance in listing terms."
The consultation closes on Friday after which the responses will be reviewed and a decision taken by HES on whether or not to list the bridge.
A Transport Scotland spokesman said: "We support the proposal to list the Erskine Bridge."
A Renfrewshire Council spokesman said: "We will assist Historic Environment Scotland as they investigate the possibility of listing the Erskine Bridge."