Editing Northern line (section)

===Formation===
{{Broader|City and South London Railway|Charing Cross, Euston and Hampstead Railway|topic=the detailed histories of the original companies}}
[[File:Electric railway train.jpg|upright=1.6|thumb|City & South London Railway train, 1890]]
The core of the Northern line evolved from two railway companies: the City & South London Railway (C&SLR) and the Charing Cross, Euston & Hampstead Railway (CCE&HR).

The C&SLR was London's first electric hauled deep-level tube railway. It was built under the supervision of [[James Henry Greathead]], who had been responsible (with [[Peter W. Barlow]]) for the [[Tower Subway]].{{sfn|Badsey-Ellis|2005|p=35}} It was the first of the Underground's lines to be constructed by boring deep below the surface and the first to be operated by electric traction.{{sfn|Wolmar|2005|pp=4 & 135}} The railway opened in November 1890 from [[Stockwell tube station|Stockwell]] to a now-disused station at [[King William Street tube station|King William Street]].{{sfn|Horne|2009|p=10}} This was inconveniently placed and unable to cope with the company's traffic so in 1900 a new route to [[Moorgate station|Moorgate]] via [[Bank–Monument station|Bank]] was opened.{{sfn|Horne|2009|p=14}} By 1907, the C&SLR had been further extended at both ends to run from [[Clapham Common tube station|Clapham Common]] to [[Euston tube station|Euston]].{{sfn|Horne|2009|pp=16–18}}

[[File:Formation of the Northern Line small.png|frame|Formation of the Northern line (Northern Heights and Battersea extensions not shown)]]

The CCE&HR (commonly known as the "Hampstead Tube") was opened in 1907 and ran from [[Charing Cross tube station|Charing Cross]] (known for many years as Strand) via Euston and a junction at [[Camden Town tube station|Camden Town]] to [[Golders Green tube station|Golders Green]] and Highgate (now known as [[Archway tube station|Archway]]).{{sfn|Horne|2009|p=26}}{{sfn|Rose|2016}} It was extended south by one stop to [[Embankment tube station|Embankment]] in 1914 to form an interchange with the [[Bakerloo line|Bakerloo]] and [[District line]]s.{{sfn|Rose|2016}}{{sfn|Horne|2009|p=27}} In 1913, the [[Underground Electric Railways Company of London]] (UERL), owner of the CCE&HR, took over the C&SLR although they remained separate companies.{{sfn|Wolmar|2005|p=205}}