The Afan Valley is situated in the west of the old county of Glamorgan. To its North is the Rhondda Valley, to the east is the Llynfi Valley, to the west is the Neath Valley and to the South the coastal belt and the sea. Even though the valley is close to the coastal belt it was difficult to penetrate because of the terrain. It was only with the coming of the Industrial Revolution that the valley opened up and this was because of the existence of large seams of coal in the Upper Afan Valley.

Before the 19th Century the horse and pack horse had been the main method of transport in the valley. But in the 1840s the railways arrived:

1842 The Glyncorrwg Railway

This was also known as Parsons Folly. It ran from Aberdulais, through Tonna, over the mountain to Tonmawr, up the side of the mountain and on to Blaencregan. Built by Robert Parsons and Charles Strange between 1839 and 1843, it opened for mineral traffic in 1842. Work carried on to try to reach Glyncorrwg, but the railway only achieved Blaencregan before finances ran out. Parsons had to pay way leaves of 4/11 a ton when at Aberdulais, they only got 4/9 a ton and so it ran at a loss.

1856 South Wales Mineral

This ran from Briton Ferry via Cimla, Tonmawr, Gyfylchi Tunnel, Cyonville, Nant y Bar, Abercregan, Cymmer to Glyncorrwg. This was the first real railway. Engineered by Isambard Kingdom Brunel the railway was of the broad gauge size, and so the tunnel through Gyfylchi mountain is worthy of note for its extra size. Although built to broad gauge, by the time it came to Cymmer it had been reverted to standard gauge as Brunel had died.

1877 Lynfi and Ogmore Extension No. 6, Maesteg to Cymmer

As an extension to the Lynfi and Ogmore Railway, its orginal intention was to enter Cymmer via a tunnel and then link up with the South Wales Mineral by way of a viaduct in Cymmer that was made of stone and iron. This was an unusual combination for railway companies, but the engineer felt that he might not get enough stone masons in the area. When the railway arrived the GWR saw the potential of the valley for the extraction of coal and so extended the railway to Glenavon Colliery and then on to Abergwynfi where they sunk the Western Colliery in 1877.

1885 Rhondda and Swansea Bay

Although it had been intended to run a railway along the length of the Afan Valley in the early 1850s, its design was too radical, in that they wanted steep inclines at the start of the valley so that the railway ran along a level contour half way up the valley side and meet the Llynfi Valley between Dyffryn and Caerau.

The RSB was engineered to run up long inclines and to reach levels which suited a tunnel through into the Rhondda Valley. The merchants of Swansea wanted some of the action and so they proposed the RSB that ran from Swansea Docks, Jersey Marine, across the river Neath via a swing bridge to Cwrt Sart, Briton Ferry, along to Baglan, then the seafront in Sandfields, through Port Talbot via the infamous crossing gates at Bethany Square, along the floor of the Afan Valley to Cwmafan, up to Pontrhydyfen, up to Argoed, Cynonville, Dyffryn, Cymmer Afan, Blaengwynfi via a seven arch bridge and tunnel with a curve, through another tunnel of 3443 yards into Blaencwm and on to Treorchy.

The Rhondda Tunnel was opened in July 1890 and was engineered by Mr SW Yockney. Again by the time the line was completed, the GWR had a controlling share of the company and before the turn of the century was owned outright by the GWR.

So by the turn of the twentieth century, the Upper Afan Valley had three working railways, but no main road.

Once the railways had arrived, the development that followed was similar to that of all other valleys in South Wales. With the influx of new workers came the building of houses, shops, churches, chapels, schools and eventually public houses. The population of the area exploded as a result of the railways. In 1831 in the village of Glyncorrwg, there were recorded 133 people, by 1871 this had grown to 303. The villages of Cymmer, Aber/Blaengwyfi and then Abercregan began to grow. By the turn of the century the villages of Dyffryn, Cynon and Croeserw were on the drawing boards.