The B6421 is a secondary road in the Wakefield area.
It starts in Castleford on the A655 travelling down Aketon Road with its speed humps. A railway line is passed under and the A639 is crossed at Traffic Lights at Cutsyke signed Acton.
The A6539 is joined and a short multiplex follows under the M62. Leaving the multiplex Featherstone is signed and reached. A Level Crossing in Featherstone is traversed. The A645 is then reached and another multiplex follows.
At Purston the multiplex ends and the B6421 then goes to Ackworth where it ends on the A628