The A6 road in Northern Ireland runs for 71.4 miles (114.9 km) from Belfast to Derry, via County Antrim and County Londonderry. While stretches of the road before Randalstown have now been superseded by a motorway, the A6 remains one of the most important arterial routes in Northern Ireland, connecting its two largest cities and urban areas. Between Randalstown and Derry, the road forms part of European route E16.

European route E16 is the designation of a main west-east road through Northern Ireland, Scotland, Norway and Sweden, from Derry to Gävle, via Belfast, Glasgow, Edinburgh, previously by ferry to Bergen, Voss, through the Gudvanga Tunnel and the Lærdal Tunnel, Lærdal, over Filefjell to Fagernes, Hønefoss, Gardermoen and Kongsvinger. In Sweden, it passes Malung, Falun and ends in Gävle.