The first section of the M621 to open, known at the time as the 'South West Urban Motorway', extended from the M62 to junction 3 in central Leeds where it used to terminate at a roundabout which was also the terminus of the M1 motorway. This section opened in stages, first from the M62 to junction 1 in 1971 (this was originally numbered M65), and then next from junction 1 to junction 3 in 1973.[1]
When the M1 was diverted away from Leeds when the 'M1 – A1 Lofthouse to Bramham' extension opened in 1999[2] adjustments were made to junction 3 and the Leeds section of the M1 was re-designated as M621, given junction 3 to junction 7).[1]