At the end of the M6 motorway at Carlisle, there is a 6-mile stretch of the A74 which links England to Scotland. This is called the "Cumberland Gap". This was caused by an argument between the British Parliament and the Scottish Parliament, which left neither the M6 or the A74(M) being built. After a lot of controversy, building started on the remaining six miles. When it is completed, there will be a complete motorway going from London to Glasgow.