The Ziegelbrücke–Sargans railway and its continuation to Chur was built as part of sections of different lines of the United Swiss Railways, which were opened independently of each other. First, the line between Chur and Sargans was opened as part of the Chur–Rheineck line on 1 July 1858. Operations commenced on the Sargans–Murg line and between Ziegelbrücke and Weesen as part of the Rüti–Weesen–Glarus line on 15. February 1859. The Murg–Weesen line was opened on 1 July 1859. Until 1875 all express trains to and from Chur ran via the Uster–Rapperswil line, as the Thalwil–Pfäffikon line of the Swiss Northeastern Railway had not yet been completed. As early as 1918, passenger traffic on the Weesen–Näfels section of the former VSB Rüti–Weesen–Glarus line was abandoned, because the connection from Glarus to the former NOB line appeared more useful. The disused section was dismantled in 1931. In the following years, the track was straightened and duplicated. First, in 1941, the Bommerstein Tunnel was relocated east of Mols. In 1961, the double-track Kerenzerberg Tunnel was opened, replacing the one-track section along the Walensee west of Murg. The old route was used for the construction of the Walenseestrasse, which required the tunnels to be widened. It now operates as the northern carriageway of the A3 autobahn. In 1969, the line between the west portal of the Kerenzerberg Tunnel and Ziegelbrücke was straightened. This involved the relocation of Weesen station from the north side of the Linth canal to the south side and the construction of a new Linth canal bridge and the Biberlikopf Tunnel. Today only very short section between Mühlehorn and Murg is single track. Today, an InterCity and an InterRegio service runs every hour between Zürich and Chur. While the InterCity trains predominantly consist of IC2000 push-pull sets propelled by class SBB Re 460 locomotives, there are also locomotive-hauled trains consisting of standard coaches and Eurocity coaches hauled by locomotives of classes Re 420 or Re 460. The InterRegios were converted to Stadler KISS at the end of 2013 and they no longer continue through Zurich to/from Basel, but they also stop in Walenstadt. This also eliminated the InterRegio services that had continued twice a day from Basel to Hamburg-Altona. These two train operated as EuroCity services, but had the same stopping pattern as IR services. At the end of 2013, the regional trains were also changed. Instead of NPZpush-pull trains, which ran from Ziegelbrücke to Chur, the line is now served by line S 4 of the St. Gallen S-Bahn using Stadler Flirt sets and stops at all the stations between Ziegelbrücke and Sargans. Weesen station has not been served since this change. Occasionally, line S 2 of the Zürich S-Bahn is extended to Unterterzen, usually on the weekend.
Freight traffic is heavy between Sargans and Buchs, because this is the transit route to the Vorarlberg and to the rest of Austria. The trains from France and the Limmattal marshalling yard to the Hall in Tirol marshalling yard use the route through the Buchs border crossing. The crossing at St. Margrethen is only used by trains to and from the Wolfurt marshalling yard. The Buchs marshalling yard serves the whole Swiss Rhine valley.
