Police were called to reports of a crash on the eastbound carriageway between junction 24 (Ainley Top) and junction 24 (Brighouse) at 9.50am this morning.
A spokesman said a van pulling a trailer had overturned, blocking part of the carriageway.
He said the driver had been able to get out of the vehicle and was believed to have suffered minor injuries only.
Highways England earlier warned drivers to expect delays while the hard shoulder and one lane remained blocked by the vehicle.
Recovery work at the scene was completed at around 12.45pm but traffic is currently queuing as far back as junction 22 (Ripponden).
The agency said drivers are facing delays of around two hours, which will take some time to clear.