Mill Hill East is a London Underground station in Mill Hill in the London Borough of Barnet, north London. The station is the terminus and only station of a single-track branch of the Northern line from Finchley Central station and is in Travelcard Zone 4. It is the least used station on the Northern line with 1.29 million passengers in 2014.The station was opened in 1867 as part of the Great Northern Railway's line between Finsbury Park and Edgware stations. As part of London Underground's only partially completed Northern Heights plan, main line passenger services ended in 1939 and Northern line trains started serving the station in 1941.HistoryMain lineMill Hill East station was built by the Edgware, Highgate and London Railway (EH&LR) on its line from Finsbury Park station to Edgware station. Before the line was opened it was purchased in July 1867 by the larger Great Northern Railway (GNR), whose main line from King's Cross ran through Finsbury Park on its way to Potters Bar and the north. The station, originally named Mill Hill, opened along with the railway to Edgware on 22 August 1867 in what was then rural Middlesex.