This motorway has recently had an increase in length due to the M1 extension. Starting from Birstall Interchange, the road spurs from the eastbound M62 and starts its downward journey towards Leeds city centre - two lanes downhill, three lanes back uphill.
The road meets junction 1 - Leeds outer ring road - where Elland Road football stadium is clearly visible. The road then becomes a 50mph zone, passing junction 2 and 2a (a small limited access junction to Beeston) before the central interchange. This sprawl of roads, completed in the late 90s, is a re-landscaped junction and allows motorway standard road to continue around the south of the city. The road swings southbound where, until the M1-A1 link road was built, it was denoted as the M1, but is now M621, and is three lanes in both directions. The road swings around the urban areas of south Leeds, hence the continuation of the 50mph zone. It eventually returns to a 70mph zone, and climbs back up towards the M62.
Just before it meets the M62 at Lofthouse Interchange, the new M1 extension comes in from the east, where the motorway is up to 12 lanes wide at a point. Lanes then split for the M62 to Hull and Manchester.