1960 Line from Bala northwards to Blaenau Ffestiniog closed to passenger services.
https://en.wikipedia.org/wiki/Bala_(New)_railway_stationNorth Wales was a battleground between the London and North Western Railway with their main line along the coast, and friends of the Great Western Railway - the Cambrian - with their line via Llangollen and Dolgellau. Between then, towns such as Denbigh, Caernarvon and Blaenau Ffestiniog could be reached by branches from both the north and the south.
Blaenau Ffestiniog remains, alone of the three I mentioned, on the main railway network (though TfW are bustituting it at present due to a train crew shortage), but it lost its service from the south in 1960. Seeing reports of passenger numbers, it was a pretty dire case of a mass transit (if you could call it that) corridor without the masses. Can't help wondering if - these days - it would attract the tourists, or be part of a political solution connecting south to north Wales while staying within the principality.
The line is also notable that part of the trackbed is now flooded by waters from a reservoir.