After World War II, each of the military governments of the Allied Occupation Zones in Germany were de facto in charge of the German railways in their respective territories.

With the formation of the FRG these successor organisations of the DRG were reunited, a situation codified by the Federal Railways Law (Bundesbahngesetz) that was ratified on 13 December 1951.

The DB was a state-owned company that, with few local exceptions, exercised a monopoly concerning rail transport throughout West Germany.

The immediate tasks in the early years after the end of World War II involved the reconstruction of the heavily damaged infrastructure and the replenishment of locomotives and rolling stock.

Contrary to the Deutsche Reichsbahn in the GDR, the DB was not subject to reparations and benefited from the influx of capital through the Marshall Plan.

Significant stretches of new high speed track, like the Hanover-Würzburg high-speed rail line, had to be laid or upgraded.

However, the merger was delayed over the structure of merged railway due to concerns by German politicians on the ever-increasing annual operating deficits incurred by the DB and DR. After several years of delays, the Bundesverkehrsministerium proposed a comprehensive reform of the German railway system (Bahnreform), which was approved by the Bundestag in 1993 and went into effect on 1 January 1994.