The A66 starts in Workington, Cumbria at the A596 and goes from west to east across the country over the Pennines through North Yorkshire and County Durham. It finishes just past Middlesbrough, Cleveland, where it becomes the A1085 to Redcar. As the A66 is a major trunk road, several sections are now dual carriageway. There is a short section running on the A1(M) about 3 miles, then forking off as the A66(M) for 2 miles to Darlington.