Since a merger in 2006, the line has been part of BLS, while passenger services have been operated by the Swiss Federal Railways (SBB) since 2010.

The constituent general meeting of the SMB took place on 30 April 1899, but for various reasons including difficulties in securing funding, construction did not begin until 1903.

[5] The largest construction site on the line was the future station area in Oberdorf, because the Weissenstein Tunnel was built from there.

[8] Although the timetable of 1921 showed the same number of services as before the war, the frequencies decreased, mainly because road transport was gradually becoming competitive.

Electrical operations under the usual Swiss Federal Railways (SBB) AC system of 15 kV at 16⅔ Hz was recorded on 2 October 1932, leading to an increase in passenger service frequency.

The further significance of the line at this time was limited to its function as a feeder to the regional centres of Solothurn and Moutier.

However, the Federal Office of Transport and the Canton of Solothurn rejected these measures in 1984, mainly because the line was still of some importance for through freight traffic and major renewal of the infrastructure was not necessary.