The first railway in the territory that is now Pakistan opened in 1861 between Karachi and Kotri, a distance of 105 miles (169 km). It was built to a gauge of 5ft 6in (1675mm), which was adopted as standard for the majority of main line railways in the Indian subcontinent.
The Pakistani railway network today is extensive, with narrow gauge lines supplementing the broad gauge in the more remote areas. There are two international links with the Indian network. A line from Quetta to the Iranian border at Mirjawa continues to Zahedan in Iran, where there is interchange with the standard (1435mm) gauge Iranian network.