Traffic on the line was never heavy until the 1960s; for many years, two
mixed trains ran a week from Lumsden. These trains carried both passengers and goods, with the usual inbound cargo consisting of
agricultural lime and fertiliser, and wool and livestock outbound. Passengers were no longer carried after 4 October 1937, and the low freight figures implied that the line was set for a slow descent into oblivion. The Mossburn Branch did not have a predictable demise, however. Mossburn was the nearest railhead to the
Manapouri hydro-electric project and the branch suddenly became very busy with traffic not only for Manapouri but also for other government schemes in the area that centred on the development of farming. Mossburn station and yard were wholly re-organised; a modern station building replaced the previous shelter shed and a
station master was appointed. A train ran from Invercargill every weekday, with allowances made for a second when required. As well as relevant freight for the Manapouri project, the line also carried significant quantities of livestock, fertiliser, and
serpentine for local fertiliser manufacturing plants. It was not until around 1980 that the various government projects wound down and required the railway less. The line reverted to a twice-weekly level of service, with trains running from Invercargill on Tuesdays and Thursdays. Traffic from this point became economically unsustainable and the branch closed on 16 December 1982, the same day as the section of the Kingston Branch from
Makarewa to Lumsden. ==Today==