|Location Map ( geo)|
|Junctions related to the A458|
Originally, this was a crossroads. In 1922 the roads to the south and north east became the A491 route between Shrewsbury and Machynlleth, while the road to the north west became the A4084 route linking the A491 to Dolgellau. In 1935 the route numbers entirely changed: the A458 was extended from Shrewsbury to Dolgellau and the A4084 switched to run south of the junction towards Machynlleth.
In 1946, the A458 was trunked. In the mid-50s, the A4084 was also trunked. The A470 renumbering took the A4084 number from the junction, after over 50 years, taking over both routes that have held that number.
|Y Trallwng / Welshpool|
|Dolgellau, Dinas Mawddwy|
|Llangurig, Machynlleth, Y Drenewydd / Newtown (A489)|
|7'6" width limit 350yds ahead / ymhen 350 llath|
|Dolgellau, Dinas Mawddwy||post-1935, now A470|
|Y Trallwng / Welshpool||post-1935, now A458|
|Machynlleth||pre-1935, now A470|
|Dolgellau, Dinas Mawddwy||pre-1935, now A470|
|Machynlleth, Llangurig, Y Drenewydd / Newtown (A489)||post-1935, now A470|