Language & WorldFact
Why trains used to stop dead at the Spanish border.
About 60% of the world's railways use standard gauge, 1,435 mm, the width of George Stephenson's early lines in England. Russia runs on 1,520 mm, Finland on 1,524 mm, Spain and Portugal historically on 1,668 mm, India on 1,676 mm. Where gauges change, trains must swap bogies or passengers must change trains, which is why many services end at borders.
Useful: A Paris–Madrid sleeper was awkward for decades, not because of politics but because of 233 millimetres.
Source: en.wikipedia.org