Since the Prussian Province of Hohenzollern (Hohenzollern Lands) was an elongated territory partly surrounded by the Kingdom of Württemberg, the line of the Royal Württemberg State Railways (Königlich Württembergischen Staats-Eisenbahnen) at this time only used the shortest route through this "foreign" area and only served the two district towns of Hechingen (from 1869) and Sigmaringen (from 1878).

In the course of the nationwide closure of branch lines, the HzL also switched passenger transport to bus service on some routes between 1968 and 1973.

[3] After extensive renovation and upgrading work, passenger traffic between Engstingen and Gammertingen was resumed when the timetable changed in December 2019.

In addition to upgrading the platforms, signalling systems and level crossings, the new Engstingen Schulzentrum station was built.

[2] Only four months after the resumption of passenger traffic, operations had to be stopped again in April 2020 because increased signs of wear were found on the wheel sets of the multiple unit.

[6] Until the timetable change in 2020, Regio-Shuttle 1 diesel multiple units in the red-beige livery of the HzL operated on the Gammertingen–Sigmaringen section.