Northern line

The Northern line is a deep-level London Underground route running between north and south London. It is shown in black on the Tube map and carries more passengers than any other line, around 340 million in 2019. The line has two routes through central London, two northern branches and two southern branches. Despite its name it does not serve the northernmost stations but does reach the southernmost station at Morden. The line’s northern termini are at Edgware and High Barnet, with a short branch to Mill Hill East. At Kennington the line splits again, sending one branch to Morden and another to Battersea Power Station in Wandsworth. The line’s complicated history began with two early railways. The City and South London Railway opened in 1890 between Stockwell and King William Street, later extended to Moorgate and Clapham Common. The Charing Cross, Euston and Hampstead Railway opened in 1907 from Strand to Golders Green and Highgate. Both companies were taken over by the Underground Electric Railways Company in 1913 and physically connected in the 1920s. Major extensions to Edgware and Morden were completed in the 1920s, with stations designed by Stanley Heaps and Charles Holden. Today the Northern line runs mostly in deep tunnels, with 38 of its 52 stations below ground. The oldest deep-level section, between Stockwell and Borough, opened in 1890. The newest extension to Battersea Power Station opened in 2021. The line’s structure reflects its history, with two northern branches, two central branches and two southern branches. South of the Thames there are 18 of the system’s 31 stations on the line, showing how far it reaches into south London.