The UK's Only Subway: The London Underground

The United Kingdom has one underground railway system: the London Underground (the Tube).

• Network: 11 lines, 270 stations, 402 km (250 mi) of track.
• Coverage: Greater London + parts of Buckinghamshire, Hertfordshire, Essex.
• Ridership: ~1.3 billion journeys/year (pre-pandemic).
• Other UK cities have light rail/tram systems (Manchester Metrolink, Tyne & Wear Metro, Glasgow Subway, Nottingham Express Transit, Sheffield Supertram, Edinburgh Trams, West Midlands Metro, Blackpool Tramway, Docklands Light Railway)—but only London has a full heavy-rail metro.

Glasgow's "Subway" (1896) is a small circular cable-hauled (now electric) system—15 stations, 10.5 km—not a full metro.