The 1949 Road Plan had proposed an Express Route between Manchester and Preston, to be achieved by improving sections of the A6 and constructing several town and village bypasses. However, by the early 1960's it became evident that there was a strong case for building a motorway, linking the proposed M62 at Worsley with the M6 near Preston.

In 1963, Lancashire County Council was appointed as the Minister's Agent Authority for the preparation and design of the motorway and the statutory procedures were completed for three separate sections.

The route of the motorway north of Chorley crossed the south end of the Lancaster Canal at three points. As the canal was already disused and rapidly deteriorating, it was agreed by the Ministry of Transport and British Waterways Board that the expense of bridging the canal was not justified. The Board therefore promoted a Bill in Parliament to denavigate the canal between Town Lane, Whittle-le-Woods and Walton Summit, a length of three miles. A scheme was then prepared by the Board to fill in the canal with a view to returning the land to agriculture, where possible, and the Ministry agreed to meet the cost of providing unsuitable material from the motorway cuttings.