Northern line

Northern line
1995 Stock arrives at Stockwell tube station heading northbound, July 2024
Overview
Stations	52
Colour on map	Black
Website	tfl.gov.uk
Service
Type	Rapid transit
System	London Underground
Depot(s)	Golders Green Morden Stabling Sidings: Highgate Edgware High Barnet[1]
Rolling stock	1995 Stock
Ridership	339.7 million passenger journeys (2019)[2]
History
Opened	18 December 1890; 133 years ago (1890-12-18) (as City and South London Railway) 28 August 1937; 87 years ago (1937-08-28) (renamed to Northern line)
Last extension	20 September 2021; 3 years ago (2021-09-20)
Technical
Line length	58 km (36 mi)
Character	Deep-tube
Track gauge	1,435 mm (4 ft 8+1⁄2 in) standard gauge
Electrification	Fourth rail, 630 V DC
Operating speed	45 mph (72 km/h)[3]
Signalling	CBTC (SelTrac)
Transport for London rail lines London Underground Bakerloo Central Circle District Hammersmith & City Jubilee Metropolitan Northern Piccadilly Victoria Waterloo & City London Overground Liberty Lioness Mildmay Suffragette Weaver Windrush Other TfL Modes DLR Elizabeth line London Trams v t e

The Northern line is a London Underground line that runs between North London and South London. It is printed in black on the Tube map. It carries more passengers per year than any other Underground line – around 340 million in 2019 – making it the busiest tube line in London. The Northern line is unique on the Underground network in having two different routes through central London, two southern branches and two northern branches. Despite its name, it does not serve the northernmost stations on the Underground, though it does serve the southernmost station at Morden, the terminus of one of the two southern branches.

The line's northern termini, all in the London Borough of Barnet, are at Edgware and High Barnet; Mill Hill East is the terminus of a single-station branch line off the High Barnet branch. The two main northern branches run south to join at Camden Town where two routes, one via Charing Cross in the West End and the other via Bank in the City, continue and then join at Kennington in Southwark. At Kennington the line again divides into two branches, one to each of the southern termini – at Morden, in the borough of Merton, and at Battersea Power Station in Wandsworth.

For most of its length the Northern line is a deep tube line.^{[nb 1]} The portion between Stockwell and Borough opened in 1890 and is the oldest section of deep-level tube line on the network. Nearly 340 million passenger journeys were recorded in 2019 on the Northern line, making it the busiest on the Underground, although this is distorted due to having 2 branches within Central London, both of which are less busy than the core sections of other lines.^[4] It has 18 of the system's 31 stations south of the River Thames. There are 52 stations in total on the line, of which 38 have platforms below ground.

The line has a complicated history. Its longtime structure of two main northern branches, two central branches, and southern unification, reflects its genesis as three separate railways which were combined in the 1920s and 1930s. An extension in the 1920s used a route originally planned by a fourth company. Abandoned plans from the 1920s to extend the line further southwards, and then northwards in the 1930s, would have incorporated parts of the routes of two further companies. From the 1930s to the 1970s, the tracks of a seventh company were also managed as a branch of the Northern line.^{[nb 2]} An extension of the Charing Cross branch from Kennington to Battersea opened on 20 September 2021, giving the line a second southern branch. There are also proposals to split the line into separate lines following the opening of the new link to Battersea.

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