THE M61 southbound was closed between Farnworth and Kearsley after a crash in which a man was injured.
One of the cars was a Renault Megane, but police said multiple vehicles were involved.
One man was injured, but escaped without breaking any bones, and police believe he was taken to hospital as a precaution.
Police are now investigating the cause of the crash, and Highways Agency officers were also at the scene.
The motorway was closed for about 1 hour and 40 minutes southbound, but one lane was reopened at 12.26pm.
Cars behind the incident were able to pass the scene before the motorway was closed, but there were tailbacks as far as junction 5 near Westhoughton.
Traffic from junction 4 was diverted to the southbound A6 and A575 and eastbound A580 to rejoin the motorway network at junction 14 of the M60.
Longer distance drivers on the southbound M6 near Preston who want to get to the M60 and M62 from the M61 are being advised to stay on the M6.
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