Thousands of motorists use the A1(M) through North Yorkshire and County Durham every day.
But anyone paying close attention to the signs as they travel north may have spotted something strange.
After Junction 53 at Scotch Corner, the next numbered junction is Junction 56 at Barton near Darlington.
So what happened to Junctions 54 and 55?
The answer lies in the complicated history of the A1(M), a motorway which was not built from one end to the other all at once.
Instead, different stretches were built and upgraded decades apart, leaving some unusual gaps in its junction numbers.
Scotch Corner, where the A1(M) meets the A66, is Junction 53.
Junction 59 of the A1m. The junction with the A167 between Darlington and Newton Aycliffe
(Image: Stuart Boulton)
Head north from there and motorists eventually arrive at the Barton Interchange, close to the North Yorkshire and County Durham boundary.
But Barton is Junction 56, with no Junction 54 or Junction 55 in between.
Official planning documents concerning the A1(M) have specifically noted the absence of Junctions 54 and 55.
The reason becomes clearer when looking at how the motorway developed.
The stretch around Darlington is much older than the motorway immediately south of Barton.
The Darlington Bypass, running between what are now Junctions 56 and 59, opened to traffic on May 14, 1965.
It was one of the early sections of the planned motorway through the North East and included Barton at its southern end.
The motorway between Junctions 59 and 63 was opened in 1969, while the stretch between Junctions 63 and 65 followed in 1970.
For decades, however, the motorway simply ended at Barton when travelling south.
Drivers leaving Junction 56 continued onto the ordinary A1 dual carriageway towards Scotch Corner, Catterick and Leeming.
Junction 60 of the A1m at Bradbury
(Image: Stuart Boulton)
That changed as part of the huge programme to upgrade the A1 through North Yorkshire.
The Dishforth to Leeming section was converted to a three-lane motorway first, with work beginning in 2009 and the upgraded road completed in 2012.
The final section between Leeming and Barton was then constructed after an interruption in the programme.
National Highways says the Leeming to Barton project was initially paused after the 2010 government spending review and removed from the roads programme before being revived in 2012.
Construction started in 2014, and the project was completed in March 2018.
That work finally created a continuous motorway-standard route between the newer North Yorkshire sections and the much older motorway beginning at Barton.
But planners did not simply start again with the junction numbers.
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Barton had long been established as Junction 56 and the existing junction numbers farther north through County Durham were already familiar to generations of drivers.
Instead, the new motorway was fitted around the established numbering.
There are similar gaps elsewhere on the route.
For example, the southern A1(M) section ends at Junction 10 before another motorway section begins at Junction 14, while the Doncaster motorway starts at Junction 34.
The gaps were left in the numbering to allow the separate motorway sections to form part of the same overall A1 route and, historically, to leave room for stretches that had not yet been upgraded.