It runs from the A580 near Wardley and heads northwest past Bolton, Horwich and Chorley to join the M6 near Bamber Bridge, just north of the junction between the M6 and M65.

The Horwich to Worsley section began on Wednesday 1 January 1969, costing £12.4 million, to open by the end of December 1970, built by the Alfred McAlpine and Leonard Fairclough & Son consortium.

However, due to the relatively short length of the M61 and wealth of alternative nearby facilities, it suffered from low traffic and footfall.

[citation needed] At the southeastern end at junction 2, the Worsley Braided Interchange, a stretch of the road on Linnyshaw Moss, earns a place in the Guinness Book of World Records for having the most traffic lanes side by side (17), spread across eight almost-parallel carriageways, in a "basketweave interchange" design.

[2][3][4] The carriageways cross each other at shallow angles and make use of tunnel-like structures to spread the load, avoiding the need for skew bridges.