M621 motorway  The M621 is a short loop of motorway in England that takes traffic into central Leeds between the M1 and M62 motorways. The first section of the M621 to open, known at the time as the 'South West Urban Motorway', extends 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, from the M62 to Junction 1 in 1971, and from Junction 1 to Junction 3 in 1973. When the M1 was diverted away from Leeds when the 'M1 – A1 Lofthouse to Bramham' extension opened in 1999 adjustments were made to Junction 3 and the Leeds section of the M1 was re-designated as M621 (Junctions 3–7).