For most of its length the Northern line is a deep tube line. The portion between and 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. 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.
For most of its length the Northern line is a deep tube line The portion between and 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 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