The North Wales Coast mainline, where it passes through the town walls of Conwy. Photograph © Brian Mottershead

The North Wales Coast Line is the railway line from Crewe to Holyhead. Virgin Trains consider their services along it to be a spur of the West Coast Main Line. The first section from Crewe to Chester was built by the Chester and Crewe Railway and absorbed by the Grand Junction Railway shortly before opening in 1840. The remainder was built between 1844 and 1850 by the Chester and Holyhead Railway Company as the route of the Irish Mail services to Dublin. The line was later incorporated in the London and North Western Railway. Between Chester and Saltney Junction the line was from the start used by trains of the Shrewsbury and Chester Railway later to be incorporated in the Great Western Railway.

In April 2006, Network Rail organised its maintenance and train control operations into "26 Routes". The main line through Crewe forms part of Route 18 (The West Coast Main Line). The North Wales Coast Line from Crewe (North Junction) to Chester and North Wales has been designated Route 22 (North Wales and Borders) and this includes the line to Chester from Acton Grange Junction, south of Warrington. The line from Shrewsbury to Chester via Wrexham is Route 14 (South and Central Wales and Borders) (until Saltney Junction).

North Wales Coast Line - Principal stations (from east to west)

• Crewe
• for West Coast Main Line
• Chester
• for West Coast Main Line
• for Wirral Line
• for Shrewsbury to Chester Line
• for Mid-Cheshire Line
• Shotton
• for Borderlands Line
• Flint
• Prestatyn
• Rhyl
• Abergele & Pensarn
• Colwyn Bay
• Llandudno Junction
• for Conwy Valley Line
• Conwy
• Penmaenmawr
• Llanfairfechan
• Bangor
• Llanfairpwll
• Bodorgan
• Ty Croes
• Rhosneigr
• Valley
• Holyhead

The line contains several notable engineering structures, namely Conwy railway bridge across the River Conwy, and Britannia Bridge across the Menai Strait.

So important was the line in the 19th and early 20th centuries to passenger, mail and freight traffic between Britain and Ireland that the world's first experimental and operational water troughs were installed at Mochdre between Colwyn Bay and Llandudno Junction. Their purpose being to enable steam engines (especially on the Irish Mail) to collect water without stopping. Later, considerable stretches of line between Chester and Colwyn Bay were quadrupled to increase line capacity but these sections have now been reduced to two tracks.

Principal through passenger services are London to Holyhead and Llandudno operated by Virgin Trains and Crewe to Holyhead, Cardiff to Holyhead and Manchester to Llandudno currently operated by Arriva Trains Wales (who replaced First North Western). A very much revised North Wales Passenger Timetable has operated since December 11, 2005 incorporating a new service to and from Cardiff every two hours. The line still provides the UK railway part of the through passenger service to Dublin using fast car ferries from Holyhead to Dublin Ferryport or Dún Laoghaire.