The M6 motorway runs from junction 19 of the M1 at the Catthorpe Interchange, near Rugby via Birmingham then heads north, passing Stoke-on-Trent, Liverpool, Manchester, Preston, Lancaster, Carlisle and terminating at the Gretna junction (J45). Here, just short of the Scottish border it becomes the A74(M) which continues to Glasgow as the M74.The M6 is the longest motorway in the United Kingdom and one of the busiest.