The B183 is the number given to the former A6 between Randalstown and Toome. It came into existance on 4th August 2019, with the opening of the A6 dual carriageway to the south.
Whe it was the A6, the section between the end of the M22 and the dual carriageway at Toomebridge was the poorest-quality stretch of the route between Belfast and Derry. The road is not as wide as any of the other sections, does not have the hard-shoulders common to many of the sections, and has a fairly twisty nature. Until it was bypassed, it suffered congestion during peak periods. Much of it is tree-lined, and there are many turnings into unclassified side roads, many dwellings, and primary school.