The A42 is a major trunk road in the East Midlands region of the United Kingdom. It links junction 23A of the M1 motorway to junction 11 of the M42 motorway. The A42 is in effect a continuation of the M42, and its junctions are numbered accordingly.

It is built to a similar standard to the M42, being a grade separated dual carriageway. The 6-mile (9.7 km) Measham and Ashby-de-la-Zouch bypass section was opened in August 1989 at a cost of £33m.

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A42 road junctions
Northbound exits	Junction	Southbound exits
Road merges onto M1 continuing towards Nottingham	M1 J23A Services	Start of road
East Midlands , Nottingham (S), Derby (A6) A453 Donington Park services		No access (on-slip only)
Castle Donington A453	J14	No access (on-slip only)
Ashby, Coalville, Leicester A511, Loughborough A512	J13	Ashby, Burton, Coalville A511
Snarestone B4116, Ashby	J12	Snarestone, Measham B4116
Start of road	M42 J11 Services	Nuneaton A444 Non-motorway traffic
Burton upon Trent, Measham A444		Road continues as M42 towards Tamworth

The A42 was built by the UK Government in 1989 to link the northern section of the M42 to the M1. Although it is not designated as motorway, and has no hard shoulder, the road is fully grade separated and runs with two lanes each way, the same as the M42 to the south.

The original planned line of the M42 saw it joining the M1 further to the north, crossing what is now the A50 Derby Southern Bypass and meeting the M1 north of Bardills Island (A52/M1 interchange)

• Donington Park services

The current road is the second incarnation of the A42. The original (1923) route was Reading to Birmingham via Oxford. The whole road was renumbered in 1935 – the section from Reading to Shillingford became part of the A329, Shillingford to Oxford became part of the A423 and Oxford to Birmingham became part of the A34. In 1993 the A423 was itself renumbered, with the section formerly the A42 becoming part of the A4074 from Reading to Oxford. The modern M42 does interchange with the former A42 at junction 4 near Solihull: Stratford Road now being numbered A34 to the north of the junction and A3400 to the south.

• Anomalously numbered roads in Great Britain.

Geographic data related to A42 at OpenStreetMap

• SABRE Roaders Digest – A42
• Road to Nowhere: A42
• Sky Vault website
• BBC news article on Sky Vault

52°45′17″N 1°26′27″W / 52.7548°N 1.4408°W / 52.7548; -1.4408 (A42 road)