A1 road (Great Britain)

The A1, sometimes used synonymously with the Great North Road, has been the longest numbered road in the United Kingdom since the allocation of road numbers in 1922. At around 400 miles long, it links the English capital city London to the Scottish capital city Edinburgh. Although its status as the principal route from southern England to the North and Scotland has been eclipsed somewhat by the advent of long-distance motorways such as the M1 and M6, the A1 nevertheless remains a lifeline for millions in England and south-east Scotland.

The A1 passes through the English counties (from south to north) Middlesex, Hertfordshire, Huntingdonshire, Northamptonshire, Rutland, Lincolnshire, Nottinghamshire, Yorkshire (West and North Ridings), County Durham and Northumberland, as well as the Scottish counties Berwickshire, East Lothian and Midlothian.

The course of the A1 has changed substantially since its inception in 1922, with bypasses having been constructed of settlements such as Grantham, Wetherby and Darlington. Some sections of A1 have been replaced by motorway, starting with the section around Doncaster in 1961, which consists of four sections scattered around England. These motorway sections are designated A1(M). The southernmost section is 25 miles long, was constructed between 1962 and 1986, and runs from the M25 at South Mimms in Middlesex to Baldock in Hertfordshire. Some 30 miles to the north is a 15-mile section in Huntingdonshire from Alconbury (near Huntingdon) to Orton Southgate (near Peterborough, Northants.), which was constructed in the 1990s. Over 70 miles to the north of that section is the oldest section of motorway in Britain, the A1(M) Doncaster Bypass, which was opened in 1961 and runs for 15 miles between Blyth, Nottinghamshire to Adwick-le-Street, Yorkshire. Less than 10 miles to the north is the southern terminus of the northernmost and by far longest stretch of A1(M), which was constructed in stages between the 1960s and 2010s, and runs from Darrington in Yorkshire to Birtley (between Washington and Gateshead) in County Durham, around 100 miles away.