Rail transport systems developed independently on the island of Great Britain and the island of Ireland. Thus, the logical division to discuss the history and present-day state of rail transport in the area is by geographical division, rather than the political division of nation states.

• Rail transport in Great Britain discusses rail transport on the larger of the British isles, comprising England, Scotland and Wales. Here, the vast majority of the railway system standardised on the standard gauge of 4 feet 8½ inches.
• Rail transport in Ireland discusses rail transport on the island of Ireland, comprising the Republic of Ireland and Northern Ireland. Here a system using a gauge of 5 ft 3 ins (1600 mm) developed.

Similarly, for the history of rail transport, rather than the current situation (described in the above articles), see History of rail transport in Great Britain and History of rail transport in Ireland.