The West Rhine Railway, or Linke Rheinstrecke, dates back to the 1840s as a gradual effort to link Köln, Bonn and Koblenz to Mainz, with the southern section between Koblenz and Mainz opening in the late 1850s. This line is well known for running along the left bank of the Rhein.

The Main Railway, or Mainbahn, was built following the completion of the Rhein-Main-Bahn which connected Mainz to Aschaffenburg. This new line was to branch off at Bischofsheim and continue along the Rhein, eventually reaching Frankfurt am Main, and was built in less than 2 years, opening in January 1863.

Combined, the Linke Rheinstrecke and Mainbahn offered a direct route from Köln to Frankfurt, and until the eventual opening of the highspeed line, made it one of the busiest lines in all of Germany. Even in recent history it remains important however, with a station built to serve Frankfurt Airport in 1972, followed by Gateway Gardens station which opened in 2019. Both of these stations are reached by means of an underground tunnel which burrows itself under the terminals of the Airport.

The lines are served by a mix of regional and intercity traffic, although most notably in the past few years, services have been strikingly branded as SÜWEX (Südwest-Express), opting for a base white livery rather than red, and using a fleet of state-of-the-art DB BR 429.1 EMUs.