Donautalbahn
The Danube Valley Railway was never conceived as one comprehensive railway from Ulm to Donaueschingen, and certainly not all the way to Freiburg im Breisgau, but came together as individual pieces of several railway projects, which were constructed over the course of about 25 years. Especially the borders between the states of Baden, Württemberg, and the Province of Hohenzollern, which became part of Prussia in 1850, made such comprehensive railway planning difficult. In just the section between Mengen in Württemberg and Immendingen in Baden, the Danube Valley Railway crosses state borders a total of ten times. The section between Ulm and Immendingen was built by the Royal Württemberg State Railways "(Königlich Württembergischen Staats-Eisenbahnen or K.W.St.E.)", while the section between Immendingen and Donaueschingen was constructed by the Baden State Railways "(Badische Staatseisenbahnen)". Prussia did not take part in the construction of the line, even though parts of it do run across the areas belonging to the Province of Hohenzollern.