The A13 heads west from Ramsey to The Cronk, near Jurby, nearly crossing from the east to west coast of the Isle of Man.
The Ballamona Straight or 'Mile Straight'
The route starts at an unsigned T junction on the A9 as it heads north out of Ramsey, and heads west on Jurby Road. This is a long, straight run between large houses set back in gardens, many of them hidden behind hedges and trees. The route wiggles a little as it reaches the edge of town, with the last few properties sitting out in the small fields beyond the main urban area. A couple of short straights then lead to a windier section through the fields with occasional roadside houses. The B14 is crossed at a crossroads, and then a long straight leads through the scattered village of St Judes, with a fine white-painted church on the right about half way along.
At the end of the straight, the A17 is crossed at another crossroads, before the road turns north west and drops down a little to cross the Lhen Trench. This is now the twistiest section of the route as it winds this way and that through the fields, a sharp left turn at the junction with the B4 turning the route back to head westwards into Sandygate. This is another small, scattered village where the A14 is crossed, again at crossroads. A few more bends lead onto a short straight where the B5 turns right, heading north west to Jurby, while the A13 curves to the south west and finds the Ballamona Straight, nearly a mile of smooth, wide, straight tarmac which forms part of the Jurby South Road Circuit, a little used route to the south of Jurby.
The route then ends on the A10 at a T junction just to the north of The Cronk. Immediately to the south, the B9 turns left again to reach the A3, but the routes con't quite make a crossroads.
As originally numbered in the 1920's, the route was given the B4 number. It had been renumbered as the A13 by 1963.