Ferrocarril General San Martín (FCGSM), named after the former Argentine general José de San Martín, was one of the six state-owned Argentine railway companies formed after President Juan Perón's nationalisation of the railway network in 1948. The six companies were managed by Ferrocarriles Argentinos which was later broken up during the process of railway privatisation beginning in 1991 during Carlos Menem's presidency.
The FCGSM took over the 5 ft 6 in (1,676 mm) broad gauge British-owned company Buenos Aires and Pacific Railway.
The principal lines departed from Retiro railway terminus in Buenos Aires to the west through the provinces of Buenos Aires, Santa Fe, Córdoba , Mendoza, San Luis and San Juan.
In the metropolitan sector of the City of Buenos Aires there is a diesel commuter branch that operates from the Retiro railway terminus in the city-centre northwest to Palomar, Hurlingham and Pilar.