From December 2011 it is used by all direct trains from Amsterdam to The Hague, and all direct supplement-free trains from Amsterdam to Rotterdam except those through Woerden.
It contains the oldest railway line in the Netherlands, and follows the old horse-drawn boat (Dutch: trekschuit) canal route from Leiden via Haarlem to Amsterdam-Sloterdijk. It was opened between 1839 and 1847 by the Hollandsche IJzeren Spoorweg-Maatschappij. The oldest section, opened in 1839, led from Amsterdam to Haarlem. Leiden and The Hague were reached in 1843, and the final section from The Hague to Rotterdam was opened in June 1847.
The opening of the Schiphollijn (1978) and the Amsterdam-Schiphol railway (1986) provided a shorter connection from Leiden through Schiphol to Amsterdam. Nevertheless, the old line via Haarlem has remained an important railway line.
In March 2015 a new tunnel and station were opened in Delft, underpassing the former railway station and viaduct. The doubling of the tracks will be undertaken until 2020.
- De Bosch Kemper, M.J. (1865). Handleiding tot de kennis van de wetenschap der zamenleving en van het Nederlandsche staatsregt (in Dutch). Amsterdam: Johannes Müller. p. 883.